ADV released Moeyo Ken OAV series, and this is some sort of continuation of it as a TV series. I'm not really sure how the timeline goes, but I think this takes place after the OAV. I only watched half of it if I remember correctly...
Anyway, the TV series throws you into a strange version of Kyoto where monsters (youkai) and humans live together, as long as the youkai have their licenses or whatever. The Shinsengumi, the good guys, and the Tsubamegumi, the bad guys, are fighting over this new way of life, and the first episode revolves around a poor little kappa. He ends up being rescued by the son of the Shinsengumi's leader, O-Ryou, and then when the Tsubamegumi tricks a huge kappa into attacking the Shinsengumi, the little kappa saves them all. Anyway, O-Ryou's son, Ryuunosuke, comes back to Kyoto and looks to be an integral part of the new Shinsengumi.
If the summary is a little weird and vague, it's because I was a bit confused at times by whatever was going on. Maybe I'll rent the OAV so I can figure it out. ;p
The series seems pretty decent overall, a action-comedy series with decent character designs and decent dialogue. I thought the characters were more fun and interesting than they looked from my first glimpse at the OAV, so while I wouldn't call it a favorite of mine, but I wouldn't mind watching more. ^^