Naoto Ôta

Five descendants of the people showered with Bio Particles by Bio Robots five centuries in the past have become Biomen. They transform with the Bio Brace and fight using their Super Electronic Brains on their masks. Their Bioswords are equipped with sword and gun modes.

A juvenile delinquent code-named Saki Asamiya is taken in by the government and forced to fight crime to redeem her actions. She is sent to various high schools to infiltrate and neutralize gangs and other forms of crime as a police officer using her metal yo-yo badge as a weapon.

Bioman must rescue two boys who possess an ancient treasure map that leads to Biobase, making them targeted by Gear.