Shō-chan no Bōken
正チャンの冒険 · しょうちゃん の ぼうけん
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
This is a fantastical story of Sho-chan, who is a journalist, and goes on adventures with his companion squirrel. This was the first Japanese manga to incorporate speech bubbles into dialogues.
Source: AniList
External databases: MADB · AniList · Wikidata
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections