The story is focused on the main character, Ichimura Tetsunosuke, an energetic, short, and very childlike 15 year old. Sadly, he and his older brother are left to fend for themselves after the vicious murder of their parents. While Tetsunosuke wants to get revenge, his pacifist brother is not so inclined. Interestingly, the story develops when they take refuge working defined jobs in a special police force called the Shinsengumi, where his brother is an accountant and he is a servant to one of the groups leaders. While there, Tetsunosuke will attempt to get stronger in order to take the revenge he so desires, but he will be confronted by the hardships that are involved with becoming that powerful.
The anime is also focused on the characters that make up the legendary Shinsengumi and the interaction and conflict they have with one another. For the history buffs, there are accurate themes that resound with Japanese history to a slight degree.