My older sister, a shut-in who's gloomy but has huge breasts and is cute, only licks my penis. (Tsukino Kasumi DKD-010)

During the winter of her second year of high school, Kasumi suddenly started staying home and never going out. For the next few years, she never left the house, living a decadent life. But in online livestreaming, which she started for tips, viewers mocked her, saying she "not only lacked good dialogue and charm, but also had no experience licking penises," and she began to notice her younger brother, Yuuto. Yuuto, who secretly loved his sister, accepted her request…