With her earphones blasting, she doesn't notice her younger brother calling out to her, and the strong hook is that he ends up staring at her as she accidentally pees. What's even better is the flow where he starts teasing her completely on her terms, saying things like "You were hard lol" and "Show me again♪". At first it's just a 'growth check' vibe, but as she stares at her younger brother's dick, her face gradually becomes more serious—that change is oddly erotic. The messed-up distance typical of incest-themed works, with their casual banter, combined with the closed-off feel of the bathroom, creates a high level of immersion. This is a hit that slowly escalates the shame and sense of taboo.