Shippai Kinshi! Kanojo no Himitsu wa Morasanai!

Summary

The Second Flower Decoration Club of Seiryuu Academy that gathers the top beauties in school is a mysterious organization of unknown activities and admission conditions. The protagonist, Shou Shimizu, due to some strange opportunity, was recommended to enter the Second Flower Decoration Club by his sister Hijiri, a member of the club. "Bro-Brother. That stain... perhaps...?" "That's not it, Hijiri! It's just spilled orange juice!" The conditions needed to join the club that are shrouded in mystery are...? Without knowing the reason, Shou, who was waiting in the clubroom for the club president Kurisu Ryuusenji, learned her secret there...! He must not let this known!! (Source: Baka-Tsuki)