One day, Kohei, the eldest son, realizes that he is dreaming when he wakes up in the morning. Kohei, who misunderstands ejaculation as a disease, pretends to be Onesho and disappears, but his mother tells him that Onesho is embarrassing and cries from an unfocused feeling. Sister Tsuna, who was immediately told the truth by her younger brother, couldn't explain it well by mouth, so she decided to give sex education in practice.
