In a plan to have humans fight each other, Gorgom used a grasshopper serum in a champaign. To help those people who already had the serum and to prevent Kamen Rider BLACK from interfering, the Rhinoceros Mutant was unleashed to help them and it first brutally killed four gang members. In the first battle, it damaged Battle Hopper (whom was revealed to have quick-healing powers). In its second battle at Honmoku Docks, he broke off the Rhinoceros Mutant's front horn and Battle Hopper rammed the Rhinoceros Mutant. The Rhinoceros Mutant was wounded by both before being destroyed by the Rider Kick.