Yasashiku shitai.
優しくしたい。 · やさしく したい
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
In order to endure his daily suffering, Ooba, a bullied child, comes up with the idea that he is saving his happiness for the future by being unhappy now. (Source: Shogakukan, translated)
Source: AniList
External databases: MADB · AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections