Yuu is Ai's serene and reserved twin brother.
His health is extremely fragile, and he frequently succumbs to illness.
He has a deep passion for drawing, and his greatest desire is to witness magic at least once in his life.
Though he loves his twin sister immensely, it remains unclear whether his feelings are as romantic as hers.
On his 13th birthday, Yuu falls gravely ill, and the Shadow of Death begins to hover around him, signaling that his time is limited.
In an effort to cure him and fulfill his wish of seeing magic, Ai ultimately resolves to become a witch.
However, this decision comes at a great cost: Yuu loses all his memories of Ai as a sacrifice to the Goddess.
