I'll Show You What I Want You to Do

Overview

Ren's problem is his sister, Rinko, and her laid-back relationships. His morning starts when he wakes up next to her latest boyfriend Kazuya, who mistook Ren's room for Rinko's. Ren's source of relief is Shirao, an older student he looks up to. Ren doesn't want to date him, thinking that being smiled at is enough, but... Through a turn of events, Kazuya discovers Ren's infatuation and asks if he thinks about Shirao at night, in bed. Ren denies it, but Kazuya, enjoying Ren's reaction, says "I'll help you out" and starts touching him. This unfamiliar pleasure, mixed with feelings of guilt, causes Ren to cry, piquing Kazuya's interest even more... What will happen to this innocent high school boy, torn between feelings of shame and pleasure, with his sister's boyfriend...? (Source: Renta!)

Source: AniList