"I want to wash my brother's foreskin with soap." "I want to see how far the foreskin of my brother's foreskin can stretch." "I want to measure the size of my brother's penis." "I want to strengthen my brother's premature ejaculation penis." "I want to take my brother's virginity." These are the desires (things I want to do) of Hibiki Natsume Hibiki, an extremely caring older sister (college graduate/working office lady) with a bro complex. She'll do it all. By the way, her younger brother is a NEET.