Title: フツーと化け物 | L24?
Book type: manga
Available formats: physical / ebook
Summary - Japanese
青春の焦燥と憧憬が入り乱れて加速するオトメ暴走譚！
対人関係がニガテな伊藤さんは
控え目だけど誰とでも仲の良いクラスメイトの高橋さんを羨んでいた。
ある日、伊藤さんは高橋さんが人を丸呑みしているのを目撃してしまう。
高橋さんは人間に擬態する化け物だったのだ！
恐ろしい怪物が平然とクラスに溶け込んでいた――そんなのって超憧れる!!
ゼッタイ高橋さんと友達になりたい！！
伊藤さんは化け物の高橋さんから、人間社会の“フツー”を教わることに。
浮かれる伊藤さんだが、高橋さんには、ある思惑が……。
異才作家×「幼女戦記」の気鋭イラストレーターのタッグが放つ
青春の焦燥と憧憬が入り乱れて加速するオトメ暴走譚！
Summary - English
DeepL translation since I’m too lazy to translate on my own:
This is a tale of runaway otome that accelerates as the frustrations and yearnings of adolescence mix and mingle!
Ito, who is not good at interpersonal relationships
Ito, who is not good at social interaction, envies her classmate, Takahashi, who is reserved but gets along with everyone.
One day, Ito witnesses Takahashi swallowing a person whole.
Takahashi was a monster that mimicked human beings!
A terrifying monster blends in with the class without a care in the world.
I definitely want to be friends with Takahashi!
Ito learns about the “normal” human society from the monster, Takahashi.
Ito is elated, but Takahashi has an agenda.
The tag team of a gifted writer and an up-and-coming illustrator of “Jujo Senki” unleashes the frustrations and yearnings of youth.
A tale of a runaway otome whose youthful impatience and longing are mixed up and accelerate!
Content warnings
Horror genre
Reason(s) for nominating: Love the questionable romance section of the horror genre and really really want to try this one
in case it explains anything I’m a big 光が死んだ夏 fan 
