One night and two days of 1 night and left alone by my wife's sister who suddenly came over

"Well, sister-in-law. Thank you very much for everything," Osamu was deeply grateful to her sister-in-law Kaori, who not only had her wife headed out on a trip and cleaned up her rough room, but also for making dinner. Without realizing that Kaori was smiling when she saw Osamu. "Osamu, can I stay here today?" Osamu agrees to Kaori's request, but he has no idea that Kaori's purpose was for Shu's body...