Kotoko finds a strange wounded boy, collapsed on the ground. She saves him and asks in return that he spend her birthday with her. She lives alone because her father had passed away… How can she still smile? And what is so unnatural in this boy she saved? It appears he can see more than human beings… What will happen to him? Will he be saved? And will he agree to spend the day with her or stay a stray and be lonely as he's been from the day he was born…?