夏合宿で人類滅亡!?

From Author Wars - https://authorwars.com/books/xia-he-su-deren-lei-mie-wang-2462172.html

Overview:

Title: 夏合宿で人類滅亡!?
Author: 藤孝剛志
Year: 2014
Type: Novels
Series: 姉ちゃんは中二病 / My Big Sister Lives in a Fantasy World
Number in Series: 3

Variant Titles:

2017. Humanity's Extinction Happens During Summer Vacation?!

Genres/Themes:

young-adult fantasy