Martial arts show with a character named Metsu The anime was based on the unarmed fighting style. The main protagonist was Metsu. I forgot the first name. it showed three different descendants in the arc. One was the era of the Shinsengumi. And two others, I can't remember.
You are very likely looking for Shura no Toki.


  Legends tell of an invincible martial art known as Mutsu Enmei-Ryu, an unarmed style that allows the user to defeat any number of armed opponents using incredible speed and strength. This is the story of three generations of those who bear the name Mutsu, and their encounters and battles with the strongest fighters of their era.


The AniDB entry is tagged with Shinsengumi.