Pink Heart Jam

Country boy Haiga has many questions he wants to learn the answers to when he moves to the bustling capital for his university life - and one of them happens to be, "do I like guys, too?" When his upperclassmen dare him to check out a box spa behind Shinjuku's Nichoume District, Haiga uses this opportunity to find out the answer to his question - and runs into his senior Kanae, who has one simple solution for him - clothes, off!
(Source: Futekiya)
Note: Chapter count includes an extra.