Shuu Hinamori is Amu's older cousin. He is an one-use, anime-only character that appears in episode 35. He still has a Heart's Egg within him, and because of that he can hear Guardian Characters when they talk next to him. In the anime, he was Amu's first love.
In a flashback, he was shown taking care of a younger Amu, and always baked for her. Though she acted like she didn't care, she actually liked his baking.