The Hero Roller is not available during regular Hero Mode. To use the Hero Roller, the player must buy an Inkling Boyamiibo and play its challenges. In these challenges, the player plays certain levels in Hero Mode, but with a Hero Roller. The Hero Roller cannot be upgraded. The blueprints for the Hero Roller Replica are received after completing the fifth boss challenge.
When the player finishes the challenge and defeats DJ Octavio, they will get the blueprints made by Ammoses Shellendorf, Sheldon's grandpappy. If the blueprints are brought to Ammo Knights, Sheldon will only give the player a replica of the blueprint as he cannot copy the technology inside. Even though it looks like the Hero Roller, it is only a replica and it has the same stats and weapon set as the Splat Roller.
"A sweet replica created by Sheldon from his grandfather's blueprints. It looks funky fresh, to be sure, but apparently it's just a regular Splat Roller with a fancy paint job..."