The brother began living with his younger brother and his wife, gradually feeling uneasy about their married life. One day, he came up with the idea to monitor his sister-in-law Kurumi, secretly recording her daily activities. As he continued filming, he discovered that Kurumi was chatting with other people online. Hiding his identity, the brother started chatting with her and learned she was dissatisfied with her marriage. On a day when her husband was away, he called her out and told her, based on their chat conversations, that he knew she felt unfulfilled. He already knew exactly what she desired. As Kurumi indulged in pleasure, he whispered, "I'll play with you again," and she happily nodded.