The protagonist, Segawa Shunsuke, has a height far below average, which makes him very anxious as a college boy. Living apart from his parents' house, he is currently living in a university dormitory together with other fellow students, but... This spring break, he received an invitation from his parents' home and returned home for the first time in 10 years. After a while, Shunsuke bides his time and arrives home, where his memories have always been of his outgrown three older sisters! Taking custody of Shunsuke too personally, older sister Asaka, who met her younger brother after a long separation, clutched him in her arms with a wide smile on her face. Almost strangling him with her huge breasts, she ended up taking him into her custody. When asked for what reason in her own home... "Anyway... the sisters want you to let them drink your sperm..." He also heard that the sisters have acute attacks of sexual desire, for some unknown reason, the symptoms of this disease occur. As a cure for these attacks, they require semen, they claim. After hearing this crazy explanation, Shunsuke did not believe it, "Can sisters have such a thing!" and was about to leave the house. At this time, however, Tsukino's second daughter arrived, locking the front doors in the hallway and all the windows with keys! The third daughter, Yuki, successfully pulled the pants off the futilely resisting Shunsuke! The little brother surrounded by his tall sisters during the mornings and evenings, under one roof during the day milked with sperm, a sex life under house arrest! Eventually Shunsuke has to cure his sisters' illness, will he be able to return safely to a quiet daily life!?...