He's my Idiotic Partner

There was once a little Girl who lives with her Grandparents in Japan Because her parents are busy working in America. One day, She met a young Boy who's a bit older than her at that time,both of them are having much fun. She seems to have feelings for him, though. But suddenly, He has to go to another country. It's really sad for both of them but he promise that one day they will meet again. As a memory, He gave her something precious that seems like a treasure from him and there story goes on..

Will he come back to japan? Will she remember him for all this years? What is that precious treasure that the boy gave him? All of these questions and problems will be Revealed and solved!