Based on the adult doujin by BOSSHI.
Niimura Akane is a normal girl whose curiosity has lead her to join the Futa Club as someone in charge of “service duties” – but first, she must pass an entrance test! Some of the members are a little bigger than she’d initially bargained for, but even with some misgivings, she’s more than up to the challenge. Thus begins her daily happenings with the four futanari within the club.
(Source: BakaBT, H-Moe)