Usagi as Sailor Moon is a heroine of justice who punishes monsters in the name of the moon! But she has a horrifyingly embarrassing secret, she developed a crush on her thirteen year old brother! She denied these feelings to herself, but Shingo showed signs the feeling was mutual. Usagi keeps noticing him glancing at her, and to her surprise she actually likes it. The tension that’s been building up between them is about to burst. Their already strong sibling bond grows even stronger with their romantic and sexual intimacy together when Usagi agrees to be Shingo’s girlfriend. Shingo thought the best romantic relationships have a little brother/big sister dynamic, and now he has one with his literal big sister, much to Usagi's delight.