Rockman is Netto's Net Navi, and devoted friend. He's basically the "good guy" of the series, as he foils the World 3's plans continuously. Rockman has a default weapon used in battle known as his "Rock Buster", in which he does not need a battle chip from Netto to use. As the episodes of the series progress, Rockman himself often becomes to prime target of the World 3's evil operators and Navis. As the series progress, Rockman begins to acquire a vast amount of various style changes. Beginning in Season 2 and all the way into Beast, these range from simple elemental changes, to soul unisons with other navis, and finally to ravenous "beast-out" transformations. Despite all their troubles with Dr. Wily or some other evil, Rockman and Netto always remain the most dedicated of friends. Rockman is a good balance to Netto's irresponsible behavior.
In the games and in the manga, the real identity of Rockman.EXE is Saito Hikari, the deceased twin brother of Netto. His father used his DNA to create a unique Net Navi.