Sakura background is a photo of KaM author. This photo includes blossom, cherry, Sakura and sky, Yoshino Yoshino, More vacant tags. To download photo (S, L, M sizes) you need to register the account and log in.
As the free account, you can download for free with some limits.
As the premium account, you can download unlimited, no waiting time, etc. Enjoin premium membership at here