Page wo Mekuru Sono Mae ni
ページをめくるその前に · ぺーじ お めくる その まえ に
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
They started off as a purely physical relationship, with neither knowing much about the other. Suddenly, he finds out that the other is a fan of his novels! At this point, it's too late to come out with the truth, so he's got to act as though he's his own fan?!
Source: AniList
External databases: AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections