[darktruth]

The first was called Shinsengumi Immon Peacemaker and Peacemaker Kurogane is the sequel to it, "Immon Peacemaker" was basically setting up the story of Tetsunosuke's determination to get into the Shinsengumi and "Kurogane" just continued it further. I think the anime of Peacemaker Kurogane is set somewhere between the two manga and moves a little into the manga version of Kurogane but ends somewhere in the middle because there was more with the story of Suzu after the Choushu raids.

As for an animated sequel to Peacemaker Kurogane anime version, there hasn't really been any news of one that I've heard but you never know, it could happen.

Also I can't believe I forgot to mention this but Saitou in Peacemaker Kurogane was hysterical! Always looking stoned lol.

EDIT: After some researching I believe the thing that gets many people confused about the manga, it's sequel and the anime version is the title that the anime used.

The scene in episode one of the anime where the Shinsengumi raided the Choushu clan was basically the conclusion of the "Shinsengumi Immon Peacemaker" manga. The "Peacemaker Kurogane" manga version continued on with the story of Suzu & Tetsunosuke after that raid while the anime used the title of the manga sequel but animated the majority of the parts where Tetsu joined the Shinsengumi clan leading up to the raids.