Kimura-kun wa Otoko Tomodachi
木村くんは男友だち · きむらくん わ おとこ ともだち
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
Miho and Tetsuo are a happy couple no matter how you look at it. Miho and Kimura have been friends since school days. Miho uses the Osaka dialect only when she talks to Kimura, and she looks really happy. Kimura knows a lot of Miho that Tetsuo doesn't know. Kimura is a narcissist, a flirt, and a talented novel editor, but he's about to get married with a younger girlfriend. So, even though Kimura passed under Tetsuo's radar, Kimura broke up with his girlfriend and quickly approached Miho!? "The thoughts of the three of us began to become entangled..." (Source: Kodansha, translated)
Source: AniList
External databases: MADB · AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections