Nishi and Akira
Both found themselves connected by a game of following the white line. Nishi is Akira's happiness, however the future of them seems to be blurry for him and so he left Nishi. After the years, they are once connected, and it lasted a lifetime and more. A bittersweet story. One of the few mangas who made me cry a river.
100/100 All time favourite.
Life Senjou no Bokura