Onii-chan ni wa Watashi ga Inai to Dame nan dakara (RJ01486412)

Due to his parents’ work schedules, Ryota Yuki lives with his caring younger sister, Ayaka.
Despite Ayaka’s constant scolding, his peaceful student life, as usual, is already beginning to crumble without his knowledge.

One day, upon returning home from school, he receives an email on his PC.
The email contains a video attachment, and upon playing it, the screen shows his sister, with whom he had breakfast, being anally trained.