Osamake: Romcom Where The Childhood Friend Won't Lose

is a Japanese light novel series written by Shuichi Nimaru, with illustrations by Shigure Ui. The series began publication on June 8, 2019 by ASCII Media Works under their Dengeki Bunko publishing imprint.

Synopsis
She smiles just for me. Her name is Kachi Shirokusa and she's even an award-winning high school girl writer! And she's beautiful! I know that she's totally out of reach for me, a normal high school kid named Maru Sueharu! But I think something's there... No, there's definitely something there! Or so I thought... but Kachi has a boyfriend?! Seeing me depressed, my friend ever since we were little who's cute, cheerful, and loves to look after others, Shida Kuroha... who also apparently had no problem telling me that she likes me for some reason just suggested, "Let's get revenge."

Characters

 * Sueharu Maru
 * Kuroha Shida
 * Shirokusa Kachi
 * Maria Momosaka
 * Tetsuhiko Kai
 * Meiko Mine
 * Mitsuru Abe
 * Rena Asagi
 * Shion Ooragi
 * Akane Shida
 * Aoi Shida
 * Midori Shida

Osamake: Romcom Where The Childhood Friend Won't Lose
A manga adaptation of the light novel, with art by Ryou Itou. It was serialised in KADOKAWA's Comic Alive and released under it's MF Comics Alive Series imprint from May 2020.

Osamake: Romcom Where The Childhood Friend Won't Lose: Otonari no Yonshimai ga Zettai ni Honobono Suru Nichijou
A manga spin-off of the light novel, focusing on the Shida Siblings, with art by Mutsumi Aoki. It was serialised in KADOKAWA's Comic Alive and released under it's MF Comics Alive Series imprint from May 2021.

Anime
An anime adaptation of the first four volumes of the light novel. It released between April 14, 2021 and June, 30 2021.
 * see: Osamake: Romcom Where The Childhood Friend Won't Lose (Anime)