Kimi To Boku No Ashiato - Time Travel Kasuga Kenkyuusho

From Fairgame:
Wanting to live with facing forward... everyone wish that they can, but there is a day that you wanted to go back, no matter what it takes. There is someone you wanted to meet, truth that you wanted to know... just to step foward from now. Door of time leaping story that makes you moved and tearful, is opened.
To a person, past can be a "support" but in a same time, it can also be "a weight". Truth is those two things are exactly same thing. Simplely, you are just using single "lump" for support or just making it to your weight. It's just how it form is decided by within your heart.