Past Day Present

Kotoko finds a strange wounded boy that collapsed on the ground. She saves him and asks only for return that he'll spend her birthday with her. She lives alone for her dad had past 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 lonely from the day he was born...