Hakoniwa Cosmos
箱庭コスモス · はこにわ こすもす
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
Nagahara Fuwa has just transferred to All Girls Private High School Cosmos and happens to get acquainted with two of the most popular girls in school, who also happen to be twins.
Source: AniList
External databases: MADB · AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections