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.
He went to Paris to study baking, and met his wealthy fiancée Eriko. Having been insecure for a long time before their engagement, Shuu's egg turns into an X-Egg and hatches in an X-Character after Eriko told him she had something that she wants to talk to him about without telling him what it was.
After his egg was purified, Eriko caught up to him and finally told him that she wants to be a patissier too, because her dream is to be with him.