The OVA, which concerns a young woman, Mikura Suzuki, and her mercenary business, the Danger Service Agency, is the spiritual sequel to Umetsu's Kite, as both feature the continuing elements of a highly trained female protagonist, extremely violent and slickly directed over-the-top action sequences, as well as graphic sex scenes. Also Sawa, the protagonist of KITE, appears in the first few minutes of Mezzo Forte when Kurokawa and the detective were speaking, Sawa walks by and looks at Kurokawa, then walks away.
Because of all the graphic sexual content present, the OVA was released both in the United States and Japan in two different versions, one with these scenes taken out and the other with them left intact, the Director's Cut. Both versions, however, retain the more violent aspects of the movie. The US release contains 20 minutes of extra footage not seen in the Japanese release, however, none of the pornographic content from the Japanese director's cut was included. The abridged version of Mezzo Forte, however, has no sex scenes and only contains two naked scenes (both showing the breasts, nipples and labia). But the shortened version is still rated 16 and up by US distributor Media Blasters.
In addition, an International Version was released in Japan on July 23, 2004. This version includes 20 minutes of extra footage, but none of the adult scenes found in the Director's Cut.
Momokichi Momoi, the mob boss owner of a professional baseball team known as the Peach Twisters, has a unique way of dealing with ineffective players – killing them. His daughter Momomi is twice as twisted as her father.
Mikura and the Danger Service Agency are hired by a mysterious old man to kidnap Momokichi. But during that attempt, they run afoul of Momomi. Before the resulting firefight, Momokichi dies when his head falls on a ventilation pipe. Now Mikura and the DSA have to come up with a new plan before they end up as Momomi's next victims.
The series concerns three characters who comprise the Danger Service Agency (DSA)
- Mikura Suzuki (鈴木 海空来 Suzuki Mikura?)
- Voiced by: Tomoko Kotani (Japanese), Melissa Fahn (English), Marie Court (English sex scenes)
- The team's combat specialist who enjoys shooting first and asking questions later. She also has a limited precognitive ability which enables her to see brief glimpses of the future, but she cannot control it. Mikura is strong, highly proficient at fighting and using firearms. She is determined, strong willed and can be a cold blooded killer if the situation requires her to be one. She is very competitive and unsociable, but she has a kind soul deep down. She also has a love of karaoke. Before the incident with the Momois, Mikura had visions which involved Momomi. In the director's uncut version, it is suggested she might have a crush on Kurokawa.
- Kenichi Kurokawa (黒川 健一 Kurokawa Ken'ichi?)
- Team leader who is an ex-cop and loves eating noodles. He is partners with Mikura and Harada in the DSA or Danger Service Agency (often referred to as the "Risk Their Lives Trio" in the press). He loves noodles, drives a yellow Volkswagen Bug, howls at hot women and always cracks lame puns. Mikura and Harada refer to Kurokawa as "Pops" for short. He likes to think that he is in charge, and more often-or-not, he does arrange jobs for the DSA. However, his knowledge in underworld dealings is valuable to the team. When the DSA was contracted to kidnap a baseball owner, he thought he recognized his face.
- Tomohisa Harada (原田 智久 Harada Tomohisa?)
- The member of the Danger Service Agency who knows about all things technical. He's a pointy-haired young man who is infatuated with Mikura, but won't admit it to himself or others. He is an expert on androids and all things technical. In the beginning, he was working on a prototype for a sex robot who acted as a prostitute and did sexual favors to those who would pay.
- Momokichi Momoi (桃井 桃吉 Momoi Momokichi?)
- The baseball owner in question. The owner of the Peach Twisters, Momokichi has had to deal with constant losing seasons of his beloved team. However, the usual tactic he employs to unload ineffective players is by killing them. He was one of the team owners suspected in "The Bloody Pennant Race", a series of killings of baseball players ten years prior. He is also an avid bowler, and would often be challenged by his daughter Momomi at a bowling alley he owned, the Peach Bowl.
- Momomi Momoi (桃井 桃実 Momoi Momomi?)
- Momokitchi Momoi's daughter. A very beautiful, large-breasted woman, Momomi is also very violent, often killing people on a whim. On all versions, she appears naked in a shower scene, which show her breasts and labia. To cross this woman would be considered suicide.
- The instances of Momomi's talent for murder and violence are many. One rumor has it that she celebrated her tenth birthday by killing someone. Another rumor says her favorite color is red... blood red. Her room decor could be described as "psychotic panda", which is a wide-eyed cartoon giant panda. In the anime, she killed the manager and the pitching coach of the Peach Twisters for threatening to leak scandalous stories about Momomi (presumably about her lesbian relationship with Sakura Sakarada, her lover in Mezzo DSA). And after Momokichi was kidnapped by the DSA, Momomi responded by taking an automatic pistol and killing her father's bodyguards for failing to do their jobs.
- Momomi, by account of her lesbian lover Sakura Sakurada, is also Mikura's half-sister, and possesses the same precognitive ability as Mikura. She had two visions that had involved Mikura, leading to an uncertain future.
- Mezzo Forte information (Japanese)