Shōjo Shikkaku

Overview

A mysterious transfer student arrives to the third year, class C for Hanazono Girl's Middle School. Akane is a plain and simple girl who was tired of her over bearing Friends, and silently thinks that it is ok for the world to be destroyed. However, all the girls of the class wake up to find themselves in a desolated school, with countdown timers. Every girl is tied to another one, and this pair must survive a 7 day Battle Royal. As it turns out, Akane is tied down to the mysterious transfer student. Friendships crumbles, hopes are lost and sanity is tested as the game starts of with a bang!

Source: AniList