You're probably asking what kind of show is this? The plot is incomprehensible, the characters are hollow panty models, and everything about it is ugly. It's your average fanservice show. The only difference is that it offers blood and real nudity. Actually, no, the ending is worth talking about. I'm not going to spoil it because that would be bad of me, but that's all there is to talk about. The ending changes it from your standard fanservice show, to one of the most baffling things I have ever seen.
For comparison...do you understand "so bad that it's good"? When it comes to movies like "The Room" or "Texas Chainsaw Massacre: Next Generation", the characters are absolutely despicable, and you knew it was going to be awful going into it. And then, out of nowhere, you get one of the most unintentionally hilarious endings ever. They're still terrible, don't get me wrong, but endings like that make it a legendary sort of terrible. I would actually recommend them to some people solely because of how they ended. Master of Martial Hearts is the complete opposite of this. Its ending is a gruesome twist out of absolutely nowhere, much like the examples I gave above, but it's a hateful change.
1. It doesn't make any sense. They try to explain it, but it takes FIFTEEN MINUTES of exposition to do that. It makes the ending needlessly complicated. The entire ending is just the twist being explained. That's no fun at all.
2. In movies like TCM4, we hated the characters and the terrible people they were, so their fates were psychologically relieving. In Martial Hearts, the characters don't have any character to speak of, so it just feels like more mindless filth only with hate behind it.
3. This show had a message they were building to. That's right, this show wants to teach us something! It's incredible what they were implying through this conclusion.
In other words, this show is hurtful to come out of. Unless you're one of those people who think "dark twists make things better" regardless of context, there is no reason for this OVA. Martial Hearts serves no purpose to anyone, this is the opposite of sexy, and this is a horrible anime. I can't recommend it out of curiosity ether, and I know you're going to dive into it anyways, but don't say I didn't warn you if you feel awful from it.