It only took a quick look at the box to see what I would be getting into with this title. It's a women-only fighting competition. Of course, it's all about how much clothing gets torn off in the process. For all the promise of titilation this show presents (the picture you see is a sleeve around the actual DVD box; the actual box has the girls with peek-a-boo torn clothes and the flip side, the part you can see underneath the DVD inside the box, has them in just panties), it never treats the characters properly for that end.
The show only cares about the main character. She spends every fight with her clothes shredded and even gets in an unnecessarily (even for this type of show) long shower scene. The fights are silly. If a close miss tears a fighter's clothes, it makes some sense. An uppercut to the chin should not explode someone's shirt! In every fight, the main character gets beaten within an inch of her life, before she makes an explosive comeback and beats her opponent in one attack. It literally takes one attack. Her opponents (the flight attendant; the teacher; the 3 sisters of the cop, the nurse, and the geisha; etc.) are all played up as more attractive, as more seductive fantasies, but the fights never drag out long enough to showcase them.
The plot feels shallow and just ridiculous, until you get to the final episode (of the 5 in the series). That one episode is about the darkest thing I have ever seen, including Gantz. It, actually, almost redeems the show. The last episode shows you what happened behind the scenes and pulls together all the seemingly random events from the other episodes. At about the 20 minute mark in that episode, you say, "Wow, they actually had a decent plot going on, here. I get it." Then, you get a Sopranos ending and... WTF? Just as they show you how good the plot was, they let you decide how it ends. No, no, no. That is a pathetic copout.
If you want a show that did this idea the right way, go find Veriable Geo (not "Neo"; Neo is the hentai version of the original); or try Queen's Blade for a more serious tone. Both of these shows glorify their characters, making them worthy of admiration. Martial Hearts got caught between a too-dark plot and a too-light handling of the characters. Skip this one.