"Mezzo Forte" is a two-episode OVA series that blends action, comedy, and elements of crime thriller. The narrative centers around the Dangerous Security Service (DSS), a private investigation agency run by Mikura Suzuki, a skilled and headstrong young woman. Alongside her are Harada, a laid-back but capable marksman, and Kurokawa, a tech-savvy operator who provides logistical support. The trio takes on various high-risk jobs, often involving criminal elements, and their dynamic is characterized by a mix of professionalism and playful banter.

The story begins with the DSS team being hired to investigate a kidnapping case involving a young girl. Their investigation leads them into a web of corruption and danger, uncovering a larger conspiracy tied to a powerful criminal organization. As the team delves deeper, they face off against heavily armed adversaries, showcasing their combat skills and resourcefulness. Mikura, in particular, is portrayed as a highly capable fighter, often taking the lead in confrontations. The series balances intense action sequences with moments of humor, particularly through the interactions between the team members.

A significant subplot involves Mikura's personal life, including her relationship with her overprotective father, who disapproves of her dangerous line of work. This adds a layer of character development, highlighting her determination to prove herself while navigating familial tensions. The series also explores themes of loyalty and trust, as the team relies on each other to overcome increasingly perilous situations.

The second episode escalates the stakes, with the DSS team confronting the criminal organization directly. The action becomes more intense, featuring elaborate shootouts and strategic maneuvers. The resolution ties up the main plotlines while leaving room for the characters' continued adventures, reflecting the episodic nature of their work.

"Mezzo Forte" is notable for its fast-paced narrative, blending action and humor with a focus on character dynamics. The series does not shy away from mature themes and graphic violence, making it suitable for a more adult audience. The characters' distinct personalities and the interplay between them drive the story, creating a balance between high-octane action and lighter, comedic moments.