This is a random draft idea of a FanFiction I thought of after reading CrazyPlatinum1899's two FanFictions about a reader getting isekai'd to "Princess Connect: ReDive".

Kokoro's Mansion, night...

It was summer and Kokoro had invited the band girls for a sleepover at her mansion. She had also invited Class 1-A, The CPUs, the CPU Candidates, IF, Compa. The Valkyries Kiana, Mei, Bronya, Seele, Fu Hua, Theresa, Sakura, and Kallen. Patrick, Ruler Jeanne D'Arc, Caster Tamamo No Mae, Saber, Shirou, Tohsaka, Sakura Matou, Illya, Mash, Ritsuka Fuijimaru/Gudao, and Hatsune Miku.

It was 8 PM now and they were gathered in the mansion's home theater which was the size of a movie theater. They were gonna watch an Anime on Crunchyroll with the huge screen. And Patrick had linked his Crunchyroll to the giant screen,

Patrick: Looks like the theater is ready. So what Anime do you band girls think we should watch?

Neptune held up her Anime.

Neptune: Look at this!

Bronya held up a HOMU Anime.

Bronya: No this one.

Blanc held up "Lucky Star".

Blanc: How about this one?

Kasumi held up "Bang Dream Girls Band Party"

Kasumi: No No. this one.

Kokoro held up "Blend S".

Kokoro: This one has smiles!

Kaminari held up "One Punch Man".

Kaminari: May I make a suggestion?

Ako held up "Rosario + Vampire".

Ako: This one is all about vampires!

Hina held up "Isekai Quartet".

Hina: This one is a crossover between multiple Isekai Anime!

Vert held up "My Next Life As A Villainess".

Vert: So many hot guys in this one.

Illya held up "Sailor Moon Crystal".

Illya: Magical girls!

Hatsune Miku held up "Dropkick on My Devil!".

Miku: "Jashin-Chan" the Anime where I starred in.

Patrick: So many options.

Mei held up "Princess Connect: ReDive".

Mei: This one.

Everyone had a vote and "Princess Connect: ReDive" won.

So we linked the projector from my laptop from Crunchyroll and the projector projected on the screen as we were about to play the first episode. All of a sudden it started to rain outside.

There was thunder and lightning. Suddenly, lightning struck the mansion and caused a power outage. A lot of the girls and some of the boys screamed. Then eyes blinked while it was dark. Then the giant screen turned on to have a black screen but with blue lines.

Midoriya: What's that?

Nepgear: I don't know.

Neptune: We'll soon find out.

Then words appeared on the screen. "You are all about to set out on an adventure. At some point in time you will all reunite."

Bakugo: What the hell is this crap?

Iida: We don't know.

Then another sentence appeared. "You will face many challenges along the way and go on many quests and adventures."

Todoroki: I've got a bad feeling about this.

Patrick: So do I. I've seen this kind of situation before.

Mineta: You don't think?

Bronya: The Bronya believe so.

Another sentence appeared. "And lastly, you will become closer than you are now."

Then a blue portal opened up from the giant screen.

Kiana: Not again with getting sucked into a TV screen!

The ones with powers tried to fight against the force but the force was too strong as they became weightless and got sucked into the portal before it closed.

Everyone was screaming as they were sucked through the portal tunnel.

Everyone: AHHHHHHHHHHHHHHHHH!!!!!!!!!!!!!!!!!!!

Illya: SHIROU!

Rimi: KASUMI-CHAN!

Seele: BRONYA ONEE-CHAN! PATRICK ONII-CHAN!

Kiana: MEI-SENPAI!

Mei: KIANA-CHAN!

Hina: ONEE-CHAN!

Chisato: AYA-CHAN!

Kasumi: ARISA!

Midoriya: KATCHAN!

Sakura Matou and Mash: SENPAI!

Neptune and Vert: NEPGEAR!

Uni: NOIRE!

Uraraka: DEKU-KUN!

Patrick and Midoriya: EVERYONE! GRAB A HOLD OF SOMEONE NOW! FORM INTO GROUPS!

Everyone had to grab hold of hands into their respective groups. The Band Girls Grabbed onto their respective band girl groups, Class 1-A got together, Shirou and his harem got together, Mash and Ritsuka grabbed hold of each other, Patrick, Kiana, Mei, Bronya, and Seele formed a group. The CPUS and CPU Candidiates held hands and so did IF and Compa. Jeanne and Tamamo grabbed onto Hatsune Miku. Fu Hua and Theresa grabbed onto each other.

Patrick: We're probably gonna get separated once we get to this other world!

Bakugo: How would you know!?

Patrick: Because of all the movies and shows I've watched and the video games I've played!

Neptune and Vert: Same Here!

Theresa: Everyone stay with your respective groups! We'll find a way to regroup!

Then there was a blinding flash of light.

(Patrick's point of view)

I woke up to find myself in an open grassy field. I regained my senses then I looked over myself. I was wearing Ras Eclair's clothing in green colors.

Then I looked to the horizon as there was something familiar about it. Then I realized something.

Patrick: This is the world of "Princess Connect: ReDive".

I looked around me and saw the Valkyries Kiana, Mei, Bronya, and Seele. They were also in different clothing. Kiana was in Kallen's old white and black clothing from 500 years ago, Mei was in her Shadow Dash Battlesuit, Bronya was wearing a version of Barbara's Church of Favonius outfit but with no cleavage showing and the sleeves were attached to the outfit, and Seele was wearing one of Ruby's outfits from "RWBY" but in white and azure colors. The Valkyries began to wake up and saw me.

Kiana: Patrick? ... Where are we?

I told them what I figured out.

Patrick: And that's it. We must have gotten sucked into the world of "Princess Connect: ReDive".

Mei: As if Seele sucking us into her game world wasn't bad enough. Now someone else does the same thing.

Seele: I apologized for doing that a long time ago.

Bronya: And all is forgiven.

Kiana: We still need to find a way back home!

Patrick: We can't get back unless we defeat Mana Senri and I've only watched up to the beach episode and don't know the rest of the first season and don't know what happens in season 2.

(I've watched both seasons by the way. I decided to finish watching the series in the past few months because of a lPrincess Connect: ReDive" X Male Reader FanFiction by CrazyPlatinum1899).

Kiana: But where do we even start?!

Patrick: By going there.

I pointed at the light falling from the sky.

Mei: That's where...

Patrick: Yes. Now let's go.

We began walking to where the light was going to land.

And that was my idea of a crossover FanFiction with "Princess Connect: ReDive". This is just a random idea I have and don't intend on making an actually FanFiction of this because it would take too long.