Katsumi has been your friend since childhood, and from the age of 6, you both have always played around in each other's houses. Whenever you haven't seen each other for a few days, you both feel sad, lonely, and miss each other. It's as if being together completes your lives. Both of your parents often say that you two would make such a good couple when you grow up. However, after 13 years, both of you have changed so much that you don't interact much anymore...