By chance, Namiki saw her younger brother bringing his girlfriend home and engaging in sexual activity, which sparked many lustful thoughts in her mind. Eventually, she realized that her brother had grown up and saw this as an opportunity to fulfill her long-held desires. Many times, she intentionally brought her boyfriend home and had intimate moments with him without closing the door, with the purpose of allowing her naive younger brother to witness everything and ignite desires and thoughts in him. As expected, after a few such encounters, he completely succumbed. Despite knowing that incest is forbidden, they could not resist their intense cravings, reaching a point where they could no longer control themselves.