Tonari no Ren-kun wa Chotto Kowai
隣の蓮君はちょっと怖い · となり の れんくん わ ちょっと こわい
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
The aggressive Ren and serious Tadaomi have been inseparable since elementary school. And even though Ren is kinda scary, he instantly melts when he's with Tadaomi. Everyone around them knows what's up...except for the two of them! ♡ (Source: Animate International) Notes: - Originally published on Twitter and Pixiv. - Includes 14 extra chapters.
Source: AniList
External databases: AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections