世界一美しい妹を抱き締めて寝ていたらいつの間にかヤンデレになっていた (Associated Names)

“If you have an incredibly beautiful younger sister, anyone would become a siscon.” Usami Aoi is a severe siscon, considering his mysterious-looking younger sister, Runa, to be the most beautiful in the world. When Aoi sprains his wrist, he starts receiving support from Runa and even begins to sleep together with her. Concealing her brother…