It's just Kenshin at the end of the series. Just thought the Battousai title fits with the other guy being an assassin.
And he's from a anime I just watched called Baccano. The part he's in is set in 1931 I believe. Might be 1932. He has superhuman agility, and speed. Able to block bullets from very close distance while also having very good skills with a gun. But he won't have a gun in this fight. Just his knife.