I went to Tokyo to take my exams and stayed at my brother's house. When I got home, my brother wasn't there and my sister-in-law, Hikari, was there to greet me. She's always cheerful and kind, and a beauty too good for my brother... I've secretly admired her since the first time we met. Apparently my brother is on a business trip for a week, so I'm alone with my sister-in-law... Her big breasts look even more beautiful with her exposed clothes, and I, a virgin, can't concentrate on my studies at all when I see her defenselessly... And then, with my sister-in-law's words, "This is a rehearsal for when I get a girlfriend," I reached my limit and finally... Oral ejaculation, creampie, facial... a total of 7 ejaculations. A 150-minute story of a Hikari's first time with the seductive and sexy Hikari.