Ani-Imo Vol. 4 (manga)

Despite his trepidations, Youta agrees to check into a love hotel with Yurika in pursuit of the two who now inhabit their bodies. Youta is pleasantly surprised by the hotel accommodations, but surprise turns to shock when he hears moans emanating from Hikaru’s neighboring room! The experience leaves Youta deeply shaken. Is he protective of his sister’s purity as her big brother, or is it because he wants to defile her himself?!