Hana Hoshino is a beautiful and innocent 18-year old girl. The man she wants to marry is 33-year-old Sakurai, her stoic and unromantic caretaker. He's the one taking care of her instead of her parents, and ever since they met when she was 14, they have shared everything in life together, both happy and sad. She wants him to see her as a woman, and escape from the relationship of "guardian" and "young lady"! Finally, on her 18th birthday, she makes a proposal to him, but...? The distance between them is a little strange (?!?). A story of love with an age gap of 15 years, involving two opposite people under the same roof.