Hikari Netto is a fifth grader at Akihara Elementry. He has a Net Navi called Rockman which is stored on Personal Terminals (PET). Two of Netto's fellow classmates Dekao has a Net Navi called Gutsman, and Meiru with a custom Net Navi called Roll. Dekao and Netto usually battle each other in the net just to prove who is stronger.
Net Navis are popular with the kids and they can have net battles which they log their PET into a computer and fight inside the computer. Each Net Navi can be customized to each individual person to their liking. while in a net battle the kids can plug in battle chips to give their Navi a weapon to fight with.
However, an evil organization called the World Three have been using Net Navi's to set terrorist attacks on computer networks and the only one to stop them is Rockman, Gutsman and Roll.