The brother (66 years old), who works as a condominium manager, is single with no marriage history and lives in the family home. His sister-in-law (60 years old) divorced last year and returned home, currently working part-time. She has no boyfriend. Since youth, the two have shared an intimate relationship—he has bathed with her, watched her develop during puberty, and masturbated thinking of her, viewing her as a sexual object. Having only had experiences with sex workers, memories of the past excite him. He feels thrilled seeing her naked while she changes, her body after bathing, or her sleeping face. His desire to commit incest with his sixty-year-old sister-in-law grows uncontrollable, and he can no longer suppress these feelings.