The Investigation Department of the Tokyo Regional Taxation Bureau, a.k.a. "Marusa." The mission of the third division of the investigation division is to detect complex and shrewd forms of tax evasion. In order to nab tax evaders, who all have very unique personalities, the members of this division have been given a certain right, which means they can act as undercover agents in their missions.This is a group of very individualistic types, with strong and unique characters, who make use of their inimitable special skills and any technique at their disposal to zero in on their targets.