Kain is a killer without mercy. An A-1 class criminal who was responsible for the destruction of 12 planets and over 250,000 murders, Kain was finally captured by the Galaxy Police, and at the cost of his own life, the Jurai emperor. He was then sealed up in a subspace prison and locked in the subspace room at Galaxy Police headquarters.

But 100 years later, Kain broke free and destroyed the G.P.H.Q., and crossed over 26 years in the past to kill one of the direct ascendants of those who imprisoned him - Achika Masaki.

(source: Absolute Anime)