So this Story 16 is about Maki as an assassin and Nico as you know a regular school girl. This idea is from NicoMaki1618. Enjoy~!
===========================

It was a normal day but it was not a normal day for a high rank assassin Maki Nishikino. She was just transferred to a school named 'Otonizaka Academy'. She was transferred to that academy because of something important she must do.

Flashback

Maki went to her dad's office. As she went in, she saw her dad sitting down on a rolling chair from her desk. "Ah..Maki, nice to meet you" said Maki's dad. "Papa, what do you want for me?" asked Maki to her Maki's dad. "Well..There's a mission that I want you to do since your age is highschool and also my daughter of Nishikino Assassin Clan" said Maki's dad. Maki sigh and spoke "Just tell me what's that mission". "Well our assassin clan has a new enemy and its called Ayase Assassin Clan. My minor personal managers were planning to asssassinate the daughter of that clan. Their daughter is a student in Otonozika Academy and also a member of U's. Since your age is highschool and also it may be nice for you to went to school since your IQ is too advance for a highschool girl. I want you to assassinate her. She has a crystal orb eyes and blond hair with a ponytail on. Would you accept that?" said Maki's dad. "Of course I'll do it papa" said Maki. "Ok, the deadline of Eri's assassination is after this month since today is February 1" said Maki's dad. "Ok papa. I'm on it" said Maki.

End of Flashback

Maki went to the bathroom and washed herself. For a few minutes after, she went out and wore her uniform. She prepared her things for school and went out. Their family's driver drove her to school with a lemo. A few minutes, Maki arrived infront of the school gate. Many student girls from Otonizaka got surprised because of the lemo. Maki went out of their lemo and walked towards in the school. The students were chatting each other about Maki. '*sigh* I knew this is so bothering. Why they want me to take school with a lemo?! *sigh*' Maki thought. The bell rang, the students went to their respective classrooms except for Maki who didn't where her classroom is.

Maki went to the faculty and noticed some teachers were in. "Umm..excuse me, I don't know what classroom I am" questioned Maki. "Umm..what would be your name?" said one of the teachers. "Maki Nishikino" she answered. "Ahh..You're my student. You must be new right?" questioned the teacher. Maki nod, "Follow me" said the teacher. The adviser started to go to the classroom as Maki followed. As they arrived infront of the classroom, Maki's adviser spoke "Wait here, I'll call you if when you can come in". Maki followed. The adviser went in and spoke "Everyone, there's a new student today. Please come in". Maki started to walk in and turn herself infront of the class. "Good morning. My name is Maki Nishikino. Nice to meet you" said Maki. "Ok Maki-san, please take your seat over there" said Maki's adviser, pointing to a vacant seat near the window. Maki walked to the vacant where her adviser pointed.

=Timeskip Recess Time=

Maki sigh because she got tired listening to the teachers. She unzip the zipper of her bag to get her snacks. Her snack is sandwich with tomato jam since she loved tomato. As she was eating her snack, two girls showed up infront of her desk. "Hi I'm Rin Hoshizora, nice to meet you nya" said the orange head girl who looks like a cat girl named Rin. "H-Hi I'm Hanayo Koizumi b-but you can call me Hanayo" said the dark-green hair girl shyly named Hanayo. "I'm Maki Nishikino, nice to meet you too" said Maki with a bit smile on.

"Maki-chan, since your popular around the school now. Do you want to join U's? Its a school idol group nya" said Rin. "R-Rin-chan, is it too early to say Maki-san 'chan'?" asked Hanayo. "Its okay Hanayo" I said and smile, "Sure Rin. I love to" said Maki. Rin jumped with joy while Hanayo was just smiling because of her shyness.

"Lets meet up afterschool on the rooftop! I'll tell the other members of our school idol group nya" said Rin. Maki nod as they continued their conversation.

=Timeskip Afterschool=

Maki went up to the rooftop to meet up with the U's members. As she opened the rooftop's door, she noticed Rin jumped to her with a hug. Maki blushed as she look at the others. "So your Maki Nishikino? Am I right?" asked Eri. "Yes I am" said Maki. "Well...Maki-chan! You're accepted to the school idol group named U's! Lets celebrate minna" said Honoka. As they were celebrating for a new member Maki Nishikino, they heard a loud burst opened from the door. They turned their head as they saw a lolicon figure with twin-tailed black hair ribbon in red. "Sorry I'm late!" said the lolicon girl. "Ahh you're finally arrive Nicocchi!" said Nozomi. Maki looked at Nico as she felt her heart pounding. Nico noticed someone staring at her as she looked at Maki. "Why are you staring?" questioned Nico. "W-Wah? I-I'm not staring at you lolicon" said Maki as she looked away. Nico got a little pissed from what Maki told. "What did you say idiot?!" said Nico. "Who are you calling idiot?!" said Maki. Nico and Maki started to argue. The rest of the U's were giggling about the argument of Nico and Maki.

=After for a few days but not in the deadline yet= (Sorry because I'm too lazy to write the rest)

Maki was inlove a bit with Nico because from spending their days arguments, friendly do and etc. Maki felt something that made her forgot to do. 'I feel something I haven't do b-but what?' Maki thought. Maki was currently in the music room, playing the piano. She closed her eyes as a vision of Eli showed up from her head. Maki opened her eyes quickly 'Oh right! The assassination... but I don't want to do it! Eri is Nico's close friend and I don't want to do it! Because Nico is my close friend. Why do I have to do this mission!' she thought as she felt herself crying. Maki heard a knocking sound coming from the door. She quickly wiped her tears with her hand and turned her head to the door. The door opened and revealing a familiar figure, it was Nico Yazawa. "Hey Maki-chan" said Nico. "N-Nico-chan? What are you doing here?" questioned Maki. "Nothing, just stopping by" said Nico. Nico went closer to Maki and sat beside her. She leaned her head on Maki's shoulder. An awkward silence occured until Nico spoke "Nee..Maki-chan, can I say something to you?" asked Nico. "Sure Nico-chan" said Maki.

Nico looked at Maki and said "Maki-chan...I-I love you...I really love you for a long time ever since we first met. I know its too early to say it but I just wanted to say this to you". Maki was surprised and blushed. "N-Nico-chan...sorry I can't accept your confess. Y-You see..I'm an assassin or an high rank assassin. I literally assassinate people but today I have a mission to do but I can't say it to you Nico-chan. So...sorry Nico-chan" said Maki as she left the music room. Nico was shocked from what Maki told her. 'B-But Maki-chan..it's okay your an assassin..I still love you' she thought as she felt her tears falling.

=Timeskip Night Time=

Maki wore her assassin suit and went out. She went to Eri's apartment to assassinate her. When she's arrived infront door of Eri's apartment, she used a credit card to unlock the door since it got lock. She slowly walked inside and went to Eri's room. She used a credit card again to unlock Eri's room door. As she got inside, she went inside slowly and saw Nozomi pictures from the wall and to the ceiling too. 'W-Wha-What is this?' Maki thought feeling a bit awkward. She saw Eri sleeping on her bed while the lamp beside her was ON since she's afraid of the dark. She slowly pulled her dagger and slowly target it to Eri and walked closer to her. After that, she felt herself weak and noticed Eri woke up. When Eri woke up she noticed an assassin beside her bed with a dagger. "W-Wha!!" yelled Eri. Eri threw a pillow to the assasssin.

"Uff!" that's what Maki said. Maki's assassin hood got off revealing her face. "M-Maki-chan?!" said Eri while she was shocked. "I-I'm sorry Eri!" said Maki as she threw a smoke bomb onto the floor to escape. Eri felt uncomfortable from the smoke bomb. When the smoke was gone, she noticed Maki isn't there anymore" said Eri. Eri's dad showed up in her room and said "Eri! Are you alright?". Eri nods as her father hugged her tight.

=Next Day=

The members of the U's except for Maki and Eri also Nico noticed thay they haven't talked each other today.(Lol BiBi) "This is weird nya" said Rin. "Yeah..." said Honoka. Maki went to her classroom and sat on her chair. 'I failed my mission...I guess my assassin is revealing..' Maki thought as she looked at the cherry blossom petals falling outside.

=Timeskip Recess Time=

First Year's Classroom

Maki was having her snack on her seat. "Maki-chan? Are you alright? You seem a bit sadden..." said Hanayo worriedly. "Hmm? I'm fine Hanayo..no need to worry" said Maki as she fake smiled. "You're not fine to me nya.." said Rin. "N-no really I'm fine" said Maki.

Third Year's Classroom

While the third year trio were having their snacks, Nico noticed her close friend Eli looking a bit pale. "Eli? Are you alright?" asked Nico to Eli. "Ha? Ohh yeah I'm alright Nico" said Eli. "Elicchi..tell us the truth.." said Nozomi. "Well..last night I saw Maki holding with a dagger and she wore a assassin suit..I don't know what she's going to do..she was suddenly in my bedroom while I was sleeping" said Eli. Nico gritted her teeth as she went to the first year classroom.

As Nico arrived in the first year classroom, she saw Rin, Hanayo and Maki eating with their snacks while having their conversation on. "Umm..excuse me but I have to borrow Maki-chan for a bit" said Nico who was behind them. "Nico-chan? Sure nya" said Rin. Maki looked at Nico in a confuse look as Nico pulled Maki outside the classroom. "Maki-chan...What are you doing last night to Eli?" said Nico as she looked down. Maki was shocked that Nico knew about that. "W-What are you saying?!" said Maki as she looked away with cross-arms. "I'm not joking" said Nico.

Maki looked at Nico as she let out a small sigh. "Well..I was going to assassinate Eli...that's my mission/goal..." said Maki. Nico was a bit shocked as she looked at Maki with an angry look. "What?! Why?!" Nico shouted. Maki felt a pierce from her heart as she said "B-Because her family are assassins also and they are the enemies of my family assassin". Nico was a bit surprised because its her first time to knew about Eli's family. She back away a few steps from Maki and run away. While Nico running, she felt her tears falling. 'Why on earth is going on today?!' Nico thought.

=Few days pass brought to you by the assassin battle= (Sorry for timeskiping because my mind was focusing for the ending)

Maki and Eli started to assassin battle each other while Nico and Nozomi were grabbed by assassins. Nico was grabbed by Ayase's assassin. Nozomi was grabbed by Nishikino's assassin. While Maki and Eli were battling, many injuries have in their arms and cheek-face. "Let Nozomi free!" said Eli as she attacked Maki. "Let Nico-chan free first!" said Maki while attacking Eli. "If I let her free first, Nozomi will get kill!" said Eli while continuing attacking Maki. "You ask for this" said Maki as her strength got increase and attacked Eli. Eli's right arm got cut as several blood came out. Nozomi and Nico got shocked and Nozomi said "Elicchi!!! No!!". Eli fell onto her knees but still has the guts to attack Maki. Maki didn't know Eli can still hold onto herself as she looked at Nozomi with a yandere eyes and moved closer to her. "M-Maki-chan? D-Don't do anything stupid to Nozomi!!" shouted Nico. "I have to Nico-chan" said Maki with a sweet smile yet evil. Suddenly, Maki felt something stabbed to her chest. It was Eli who stabbed Maki with a dagger. "M-Maki-chan!! No!!!" said Nico. Nozomi and Nico let them free as Nico crawled to Maki and said "M-Maki-chan...d-don't leave me..". Maki has still a remaining for her to speak Nico. "N-N-Nico-chan... D-Don't worry..I'm still beside you n-no matter what" said Maki as she die. Nico felt her heart stabbed but didn't stabbed for real. She hugged Maki tightly as she screamed Maki's name.

The End

===========================
Sorry if it has error because my hands are tired from typing this story. So..you can still tell me what ideas or AU you would like to read for NicoMaki. Bye~! ♡

Updation: Any genres would do for your ideas. :3