Houyou

From Evil Empire:
Tamaki's parents divorced when she was a child. Her father moved out, taking her brother, Kyousuke, with him. Now 11 years later, Kyousuke has returned for a visit. Because of the stress of the divorce, he has forgotten nearly all of his childhood memories of his mother and sister. Is that why Tamaki has a hard time viewing him as a brother? Or is it his "male aura?"

Their reunion is complicated by the reappearance of Tamaki's on-again-off-again boyfriend, Hayato. Tamaki and Kyousuke end up getting into a fight over Tamaki's vague notions of what constitutes love. Will Tamaki's anger with her brother end up driving her into a threesome with Hayato and another boy?