15 de Shoujo wa, Are ni Naru.
15で少女は、あれになる。 · じゅうご で しょうじょ わ あれ に なる
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
The women of our planet are being targeted by an alien species for food, so it has become customary for a 15 year old girl's left arm to be infested with a young attack-type alien. In other words, girls are the strongest thing on the planet right now.
Source: AniList
External databases: MADB · AniList
How to compare editions, collected volumes and ISBNs / Sources, updates and corrections