Koihime Musou is based on an adult PC adventure game, in a Romance of the Three Kingdoms style. It's a 12 episode series from Dogakobo and Marvelous Entertainment.
Big breasted "black-haired bandit hunter" Kannu travels from village to village taking out bandits. When she arrives in a new town, she's practically run over by a group of children calling themselves the Rinrin Bandits. The Rinrin Bandits are led by a girl named Rinrin, and the wreak mischievous (though harmless) havoc on the town. Rinrin's parents were killed by bandits, and she now lives alone. The kids are mostly allowed to run rampant, but they've gone too far this time by drawing on the chief's wall. That's the last straw for him, and he insists that Rinrin be arrested and punished for her actions. The townsfolk believe she likely won't be killed, but a harsh whipping might occur instead. Kannu offers to take care of it herself in order to protect the child from such a punishment.
One of the children overhears this and they gang up to protect Rinrin. Kannu easily escapes their traps and explains to them that she won't turn Rinrin in. But when she finally locates Rinrin (or Chouhi as she calls herself), she discovers that the child is not to be taken lightly. Indeed she gives the older and more experienced Kannu quite a workout well into the evening before finally conceding the battle. It's clear that Chouhi is just lonely, and she invites Kannu to stay the night with her. Kannu explains that her family was killed by bandits as well, and that she chooses to fight against them instead of become one of them. By morning Kannu has convinced Chouhi to travel with her to help her change the world.
The animation is good, though they randomly jump to chibi characters for no real reason. Nothing about the story has grabbed me so far, but I plan to check it out for a few more episodes to see what the over arching story will be about. There's nothing particularly amazing about it really, though if you liked the game, I suppose you'll like this as well. I'm still waiting for some nice looking guys, but I won't keep my hopes up. In fact, I haven't seen any evidence of any sort of major male character appearing in the show, which isn't really a complaint so much as me just overwhelmed by all the boobage. There's nothing really notable about the opening and ending sequences. The opening presents a large assortment of characters, and the ending shows them all chibi-sized.