Serious and generous, but a bit shy, Yuudai has been unsuccessful with the opposite gender. Chizuru is an energetic and cheerful girl, but when it comes to boyfriends, she's been unlucky and clumsy, and never had a steady relationship. This is the first Christmas the couple spends together. Chizuru loves animals and Yuudai plans to give her a rabbit in a box, but it turns out to be... a mini donkey?! As the funny creature escapes, Chizuru goes after it, and Yuudai loses sight of them both!