Katsumi's POV:

Me and Shibata-kun finished our sports session after school and headed to Rina's Restaurant to buy some milkshakes and talk. Somehow, um... it ended up becoming a revision session with all his friends in C Class?!

Because I was exhausted, I didn't bother changing out of my jersey, so I didn't have my tie on. Due to this, I could blend in and make our meeting seem... less scandalous, because I'm in E Class while Shibata-kun's in C Class.

Shibata-kun did change however, but he wore his uniform very loosely with his sleeves rolled up. His tie was barely put on properly, which was... kind of cute... Taking a sip of his strawberry milkshake, he wiped the brow of his forehead.

Ah, I'm gonna melt! He's so cute and cool! Even as he flipped through his notebook, he looked so awesome!

Sitting next to him was his buddy Sugiura Motofumi-san, also in C Class. He was in the art room after school, and as we headed out, he joined us. Sugiura-san's an amazing artist!

However we both sucked at academics. Surprisingly, despite not looking like it, Shibata-kun was actually pretty smart. Since we had a physics test tomorrow, he offered to help study with us.

"Forces and elasticity. This one's short, so we can go through it in less than hour." Shibata-kun smirked and pointed at it in his book.

Sugiura-san was doodling in his sketchbook while he paid attention. He was lanky and had bleached hair with some highlights. Yep, definitely artsy. Last month, he had all sorts of colours in his hair.

"So, Katsumi-san, Sugiura, do you know what forces are at least?"

Shibata-kun was like the opposite. He was muscular and had strong legs. His hair was brown and fluffy. He took good care of his body and appearance!

"Forces are responsible for changing the motion of objects... right?" Sugiura-san had an lethargic voice. He seemed like he was tired all the time.

Considering how impressive his art was, he must've stayed up late to paint it!

"Yep. When a force acts on an object, it can change shape by bending, stretching or compressing. Maybe even a combination of all three changes."

Sugiura-san turned a page in his sketchbook and began scribbling images of objects being bent, stretched and compressed. That was a good way to remember! To draw it out!

I tried doing the same. Shibata-kun laughed at the both of us.

"Pay attention and stop doodling."

"But it helps me remember..." Sugiura complained.

"If I draw it, I'll definitely remember!" I exclaimed.

"I don't think those crude drawings'll help you." He shrugged. How mean...

"Yeah, Katsumi-san... I don't think you should draw. That art's kinda crap."

I felt more depressed than before. I closed my notebook and rested my head on the table.

"I mean, don't you remember more by talking about it? That's how I remember stuff. Talking about it." Shibata-kun said.

"Oh! That's true. I remember things about sport techniques or training because I talked to you about it."

"Yep. Just gotta apply it here."

"You're so smart, Shibata-kun!"

"She hasn't met Houki-san or Murakawa-san yet, clearly." Sugiura-san sniggered.

"I know Houki-san because Ria-san doesn't like her. I don't know who Murakawa-san is, though."

Sugiura-san drew a sketch of Murakawa-san and presented it to me. Ah, it was the guy with glasses and a mushroom hair cut... yeah, he looks like the smart type.

"I guess for Sugiura, he remembers stuff by drawing it." Shibata-kun nudged him. "Anyways, to change the shape of a stationary object, there must be more than one force acting on it. Sugiura, can you illustrate my examples?"

"That's my only skill, chief." Sugiura-san smirked and twirled his pencil.

"You need one or more force to bend an object's ends past each other. For example, when an archer pulls an arrow back against a bow."

Sugiura-san drew a simple bow and Shibata-kun pointed out where to place the force arrows. Sugiura-san put two at the end pointing up and down, and one at the end pushing it down.

"You also need more than one force to pull an objects ends apart. For example, when a rubber band is stretched."

Sugiura-san drew a rubber band and drew two arrows going the direction it got pulled.

"And finally, push an object's ends together. For example, when an empty drink can is squashed."

Sugiura-san drew a drink can being squashed and Shibata-kun told him to draw two arrows pointing at the can.

"A change in shape is called distortion. There's two types, elastic and inelastic. Elastic distortion is reversed when the force is removed, like the rubber band. Inelastic distortion is not fully reversed when the force is removed. It's a permanent change in the shape, like the can that got squashed."

"So if it's elastic, you can put it back to normal, but if it's inelastic, it's not?"

"Yeah. It's like if you tore your jersey. You can sew it back together. If you broke your trainers though, there's no way to salvage that."

I shivered. My trainer's breaking would be the worst. I spent a lot of private points on it!

I drank some of my banana milkshake as a reward for studying. Ah, so sweet and refreshing!

"Remember when Ike-sensei taught us Hooke's law? Shibata-kun asked us.

Sugiura-san shook his head no and called for a waiter. I put my finger to it and thought really hard.

I remember this vaguely... but from where?

"Is there anything I can get you?" Tsuji-san came up to our table with a smile.

Hmm... Hooke's law was definitely an equation, because I hated that it was maths.

"Yeah, can I get chilli fries with extra chillies? I'll pay now." Sugiura-san said, handing Tsuji-san his phone.

Force... it has to relate to force, since it's what we're revising...

"Sure." Tsuji-san punched his order into the machine, took his phone, scanned it into the device and handed it back. "I'll be right back with your order!"

"Need a hint, Katsumi-san?" Shibata-kun asked.

"Yes..."

I conceded.

"Well, let's talk about extension and compression first. Extension happens when an object increases in length, and compression happens when it decreases in length. The extension of an elastic object, such as a spring, is described by Hooke's law."

Sugiura-san blinked. "Oh, I got it. Force = Spring constant x Extension."

Guu! I got beaten out!

"Huh, good job. Not even I remembered that." Shibata-kun laughed. "Had to check my book. Anyways, yeah, that's right. It's easier to remember as F = k x though, in my opinion."

"What do the things stand for?" I asked.

"F is force, which is measured in Newtons (N). K is the spring constant and is measured in Newtons per metre (N/m). X is the extension, or increase in length, and is measured in metres (m)."

"Oh, the K is like the one in proportion. The constant!"

"Why does physics have to be 40% math..." Sugiura-san clicked his tongue and drew a self deprecating drawing.

"I feel the same way..." I sobbed, feeling his pain.

Shibata-kun shrugged. "Physics' easy to grasp. Just learn the formulas, like Hooke's Law."

"Not everyone is smart as you, Shibata-kun!"

"I'm not that smart. I just barely get by. My score on the exam was crap."

"You should've seen his English score. It was worse than mine." Sugiura-san laughed.

"I think 2 is good... considering I don't know much vocabulary."

"2 is trash."

"Shut up, 3."

I covered my mouth and began laughing.

"My English score is even worse. I got 1."

"That's something not to boast about, Miss..." Sugiura-san said.

"Here's your chilli fries, Sugiura-san." Tsuji-san walked to our table and placed a delicious looking, crispy batch of chilli-drenched fries on the table. Cheese and pickled jalapeños melted over the top.

I wiped my mouth. It looked way too good.

"Legend." Sugiura-san took a handful and shoved it in his mouth. "Compliments to the chef."

"I'll be sure to tell them."

Just as Tsuji-san was about to leave, Shibata-kun grabbed her sleeve.

"Hey, Tsuji-san, can you give us a question for us to do? For Hooke's law."

"Ehhh? I'm not good at science..."

"You can make one up. I just want to show these two how it works."

Tsuji-san's face went red. "Um... Hooke's law, huh? F = KX? Um... a force of 3N is applied to a spring. The spring stretches by 0.15m. Calculate the constant."

"You do know what it is, don't you?" Shibata-kun smirked.

"Nonono! It's by accident I came up with it!" Tsuji-san cried.

"But rearranging is pretty complicated, isn't it?"

"Tsuji-san, stop flirting with the customers and get back to work! Table 12 needs a waiter, and table 18's order is ready to go out! I can't do this by myself!" Keisaki-san shouted across the restaurant.

"Y-Yes sir!" Tsuji-san scurried off.

"Anyways, spring's being stretched is an elastic distortion. It'll go back to normal. She gave us 3 N and 0.15 metres, right? So make the equation equal to K. K = F / X. Plug in the numbers and you get 20 N/m."

Sugiura-san didn't pay attention and was too busy eating his delicious fries. I really wanted some... but I can't because I'm on a strict diet and need to keep a healthy body so I can play at top performance. I'm already cutting it by drinking this delicious banana milkshake...

"Spring constant is a measure of the stiffness of a spring up to its limit of proportionality, or elastic limit. The limit of proportionality refers to the point beyond which Hooke's law is no longer true when stretching a material. The elastic limit of a material is the furthest amount it can be stretched or distorted without being able to return to its previous shape. Once it's gone past the elastic limit, the distortion becomes inelastic."

I tried to concentrate, but couldn't because Sugiura-san was eating those super delicious-looking chilli fries. I really wanted some...

"So essentially... the limit of proportionality is when, um... Hooke's law is longer true...? Elastic limit is how far something gets elastic distortion... then becomes inelastic distortion."

Shibata-kun nodded yes.

"The higher the spring constant, the stiffer the spring."

Sugiura-san suddenly wheezed.

"Did those chilli fries go down the wrong way?" Shibata-kun glared at him.

"N-no... don't worry..." Sugiura-san coughed and began to draw something in his sketchbook.

"The spring constant is different for different elastic objects. For a given spring and other elastic objects, the extension is directly proportional to the force applied. For example, if the force doubled, the extension doubles. This works until the limit of proportionality is exceeded."

"Yo, you guys like my spring d*ck?"

Sugiura-san showed us his drawing.

I screamed on the inside.

Shibata-kun snatched the book out of his hand, ripped out the page and chucked the book back at him.

"Watch your back, cuz on the way home I'm throwing this at you." Shibata-kun tossed the ball of paper in his hand.

"Ke ke, it's funny."

"Dude, there's a girl sitting in front of us. Keep it in your pants."

"Whatever, white knight Shibata-san."

"I am not a white knight."

"Ke ke ke."

I scratched my cheek.

"Now pay attention. If you can't concentrate, leave. Katsumi-san's trying her hardest." Shibata-kun said.

"Yea yea. Go on."

"When an elastic object is stretched beyond it's limit of proportionality, the object doesn't return to its original length when the force is removed. In this instance, the relationship between force and extension changes from being linear (directly proportional) to being non-linear. Non-linear extension occurs more in some materials than others. Materials like clay or putty usually show non-linear extension."

"It seriously sounds like you're talking about making your d*ck longer, Shibata-san..."

"What is with your obsession with d*cks?!"

"I didn't become a good artist without drawing enough d*ck and p*ssy to last me a life time."

"Get your priorities straight, man! Jeez!"

"Ke ke ke... I wish I could. The only reason I'm in C Class is because of my art skills, obviously. I suck at everything else."

"Heh. I feel you, though. I think I'm only in C Class because of my athleticism. If not, I'd probably end up in D Class with the rest of the delinquents."

I scratched my cheek.

Shibata-kun's good at sports and has an okay academic score. That's why he's in C Class.

Sugiura-san's really good at art. That's why he's in C Class.

Then why am I in E Class...?

I've always thought about "why". But I could never think of a good reason how I ended up in that class.

I'm good at sports like Shibata-san, but not as good at academics. But Yukimura-san is also in our class, and he's really good at sports too. Though, it's because of his behaviour he got sent to E Class.

Sure, I'm a little childish and clumsy... but is that really reason enough to be sent to the bottom...?

"Oh, I'm not trying to insult you, Katsumi-san. You're a brilliant athlete too." Shibata-kun said.

I shook my head no.

"It's not that. I just... don't know why I was put into E Class."

"You probably suck at something." Sugiura-san bluntly said. "Have you figured it out?"

"Um... not really. I know I'm bad at academics, and that I'm clumsy."

"You're not as bad as those other guys in E Class, Katsumi-san. I think you can move to D Class." Shibata-kun encouraged me.

"He he... I hope so."

That's the key word here. "Hope".

E Class, a class for defectives...

What makes me defective...?

This entire time, I've just been... lying to myself.

"Sugiura-san drew a good graph showing the force-extension proportionality. It's direct until a certain point, and then tapers off. Linear extension and elastic distortion can be seen below the limit of proportionality."

Denying this part of my past because... I'm so ashamed.

...I reached that conclusion a long time ago.

Since May 1st, I secretly knew why I was relegated into E Class.

"Non-linear extension and inelastic distortion can be seen above the limit of proportionality. The limit of proportionality is also described as the elastic limit."

But my cowardice never let me accept this was the truth.

If everyone found out, they'd hate me...

I'm defective because... of my lack of action.

My inability to do something in the moment...

"The gradient of a force-extension graph before the limit of proportionality is equal to the spring constant."

If I could've moved... spoke... did something... anything...

I could've saved that person.

Because I was selfish, they...

They...

Shibata-kun was clicking his fingers in front of me.

"You good? You were spacing out."

I blinked and rubbed my misty eyes.

"Yes... I'm fine."

"This is pretty tiring, I know. Just hold on a little longer."

"Yeah... I can."

I don't know if I really can hold on when this guilt eats at me.

But like usual, I'll try to forget about it, since deep down, I know that I'm trying to make up for it.

Because that person is here in this school.

"You guys are aware of the concept of "work"?"

"Energy transferred by a force, right? There's an equation to go with it..." I said. "Um, work done = force x distance moved in the direction of the force?"

"Hey, that's a perfect answer. Work for springs is done when the spring gets extended or compressed. Elastic potential energy is stored in the spring. As long inelastic distortion hasn't happened, the work done is equal to the elastic potential energy stored."

"What's elastic potential energy?" I asked.

"Its energy stored in squashed, stretched or twisted materials. So, a slinky is the most obvious example. It has elastic potential energy when you stretch, squash or twist it. You can calculate the elastic potential energy stored with this equation: elastic potential energy = 0.5 x spring constant x extension^2."

"Oh, so it's like the kinetic energy formula. 0.5 x mass x velocity^2." Sugiura-san said.

"Yep. The elastic potential energy (Ee) is measured in joules (J), the constant (K) is measured in newtons per metre (N/m) and extension (X) is measured in metres (M). You can write us as Ee = 1/2kx^2 if you want. This equation also works for the reduction in length for when a spring is compressed."

"Do we have to do an example?" I asked, quivering.

"Ha ha, let's just skip over it. The last part of this is the practical. You did it?"

"Nope... we rarely get to do practicals because of our cruddy classroom being unsuited for experiments."

"Then... me and Sugiura can explain!"

Sugiura-san, with a mouth full of chilli fries, looked at Shibata-kun like an alien.

"I need your art expertise to illustrate it to her."

Sugiura-san rolled his eyes and nodded, sucking the chilli off his fingers and rubbing them in a paper napkin. Swallowing, he drew up the apparatus.

"Basically, we're investigating the relationship between force, extension and work done extending a spring. Firstly, you secure a clamp stand to the bench and use bosses to attach two clamps to the clamp stand. Make sure the clamp stand is secured with a large mass for the base of a G-clamp. You attach a spring to the top clamp and a ruler to the bottom clamp. Adjust the ruler so that it's vertical and with its zero level with the top of the spring. You measure the and record the unloaded length of the spring."

"Seems simple enough..." I muttered.

"That's just setting it up. Now you hang a 100g slotted mass carrier - with a weight of 0.98 Newtons - from the spring. You measure that new value and record it. You then add another 100g slotted mass and record again. You just continue doing this until you added 1,000g worth of slotted mass."

"Your results would look like this, if I'm not mistaken." Sugiura-san said. "I was forced on record duty, so I kinda got it beaten into my head."

Force (N): 0 (unloaded)
Length (mm): 22
Extension (mm): 0

Force (N): 0.98
Length (mm): 52
Extension (mm): 30

Force (N): 1.96
Length (mm): 83
Extension (mm): 61

"And so on and so forth." Sugiura-san said. "This is the extension-force graph you'd get. You'd figure out each point by doing "extension = length - unloaded length"."

It was linear until the end, when it started going up.

"The analysis of the result tells us that the region where extension is proportional to force, the gradient of the line is a reciprocal of the spring constant, k. Work done = force x distance moved, so the work done here is extending the spring, which you can find by calculating the area under the line of the graph. The energy transferred to a spring's elastic store is given by E = 1/2k^2, right? So, you can compare the area under the line, from the origin up to a point, with the calculation of the energy stored in the spring for that extension."

"It's important to keep the ruler vertical. There're a couple hazards. Like equipment falling off the table, masses falling to the floor if the spring fails, and the most dangerous, the sharp end of the spring recoiling if the spring breaks. You can prevent this and avoid the consequences, like bruises, cuts and damage to the eye. Just be careful, be gentle when loading masses, and wear proper protection, like goggles." Sugiura-san chimed in.

"Anyways, besides that, this is the entire forces and elasticity unit done. That wasn't so bad, was it?" Shibata-kun smiled.

Ah, my heart felt so relieved knowing I didn't have to do this anymore.

"And just in time to go get the bus back." Sugiura-san checked the time. "Well, we better head out or else we'll be walking home."

Shibata-kun suddenly chucked a ball at Sugiura-san's head.

"Ow..."

"I told you to be careful. Katsumi-san, you taking the bus home too?"

"Yeah, but a different one. Since I need to go back to the Drachma Red area."

"Ah. Alright, well, I'll see you tomorrow then?"

"Sure! Let's continue practicing our long distance."

"Yeah, that'd be great. Maybe I'll even send a surprise message." Shibata-kun grinned cheekily.

"Says the guy who told me to keep it in my pants." Sugiura-san shoved him out of the booth. "Just air him if he messages you."

"Geez, that's cruel of you, man." Shibata-kun laughed and grabbed his bags.

I probably won't be able to message Shibata-kun tonight, even if I wanted to. It'd be great to talk to him more. I really like our conversations.

But I needed to focus my time elsewhere. With that person.

I shut my bags and slung my bag on my shoulder.

I hope today I can see his smile too.