☆Working as a condominium manager, the older brother (66 years old) is single with no marriage history and lives at his parents' home. His sister-in-law (60 years old) divorced last year and returned to the family house, currently working part-time. She has no boyfriend. The brother has always been close to his sister-in-law since youth, and while bathing together and watching her grow up, he gradually began seeing her as a sexual object. His experiences with sex workers have been limited, and recalling past memories makes his heart race. He gets excited just seeing her naked body while she changes clothes, her post-bath appearance, or her sleeping face. He can no longer suppress his intense desire to establish a physical relationship with her, his sixty-year-old sister-in-law.