The show is set during the Meiji revolution and features many actual historical characters (even if they are somewhat dramatised and altered to fit the storyline). The plot itself actually centres on Yojiro a youngman who is known as the Eternal Assassin it is his destiny to prevent a powerful mystical object known as the Conquerors head from falling into the wrong hands. However he fails and the head takes possession of Enomoto eventually leading to civil war. As such it becomes Yojiro's job to kill Enomoto and end the war.
As i have already said this is a very confusing anime and the plot can be very difficult to follow even if you do know who everyone is and have a vague idea of the historical setting. However, it is original, fast paced and very well acted.
All in all it is a very nice addition to the historical anime genre.moreless