|“||Damn Godzilla, you're mistaken if you think your powers are a match for Mechagodzilla.||„|
Kuronuma is the leader of the original invasion force of the Black Hole Planet 3 Aliens and the secondary antagonist in the film Godzilla vs. Mechagodzilla.
Kuronuma was the leader of the first invasion force sent by the Simians to Earth. Kuronuma ordered the disguised Mechagodzilla to be sent to Japan to wreak havoc and destroy Tokyo. Along the way, Mechagodzilla was attacked by Godzilla's ally Anguirus, who saw through its disguise. Mechagodzilla defeated Anguirus and marched onto Tokyo, where it encountered the real Godzilla. Kuronuma, surprised that the real Godzilla appeared so quickly, ordered Mechagodzilla to shed its disguise and kill Godzilla. Godzilla was seemingly killed in the battle, while Mechagodzilla's head controls were damaged. Kuronuma bitterly decided to postpone the invasion and recalled Mechagodzilla to the Simians' base in Okinawa. Kuronuma discovered that none of his men had the expertise to repair Mechagodzilla in time to meet the timetable for the invasion. Kuronuma had his men kidnap Hideto Miyajima, a prominent Japanese scientist, and force him to work on Mechagodzilla, or else his daughter Ikuko and her friend Masahiko Shimizu would be executed.
Miyajima fully repaired Mechagodzilla, much to Kuronuma's satisfaction. Kuronuma offered Miyajima a glass of wine in celebration for his accomplishment, but Miyajima demanded to see his daughter and Masahiko. Kuronuma calmly agreed to set them free, and led Miyajima to the execution chamber, where they were being held. After the doors were opened, Kuronuma pushed Miyajima into the chamber, deciding he had outlived his usefulness. Unbeknownst to Kuronuma, Masahiko's brother Keisuke and INTERPOL agent Nanbara had infiltrated the base, and freed Miyajima and the others. Kuronuma rigged Keisuke's car to explode once they had escaped the base, and assumed they were dead after the car started and exploded. In actuality, Nanbara anticipated the trap and started the car with a wire. While the rest of the group went to awaken King Caesar, Nanbara, Masahiko, and Miyajima re-entered the base to "take care of those bastards." Kuronuma anticipated their return, and captured them. Kuronuma applauded the fact that they had survived for so long, and forced them to witness the activation of Mechagodzilla.
While Mechagodzilla battled King Caesar, Godzilla suddenly appeared, much to Kuronuma's surprise. Kuronuma ordered Mechagodzilla to beat Godzilla to death, and watched the ensuing battle. The combined might of Godzilla and King Caesar was enough to defeat Mechagodzilla, and an exasperated Kuronuma watched as Godzilla tore the head off of his robot. At that moment, Miyajima and the others broke free from their binds and Miyajima used his special pipe to sabotage the machines in the base. Kuronuma drew his gun, but was shot in the throat by Nanbara, causing him to spurt blood and fall over, dead. As Kuronuma lay dead on the floor, his human disguise faded away and revealed his true form.
Kuronuma is brutal, overconfident, and has absolutely no regard for human life. Kuronuma pretends to be a polite, calm gentleman, but in reality is a murderous sadist. Kuronuma forces Miyajima to fix Mechagodzilla in exchange for his daughter's life, then orders him executed along with his daughter as soon as he finishes the job. Kuronuma's overconfidence proved to be his undoing, as he believed the Earthlings were incapable of stopping him. He didn't bother to check if the humans survived the car bomb, and paid little attention to his three prisoners during the battle between Godzilla and Mechagodzilla, allowing them to break free and ultimately kill him.
- "I didn't expect the real Godzilla to appear so soon. The Earth people must be astonished." - Kuronuma, after the real Godzilla appears to fight Mechagodzilla
- "Enjoy this night. It will be your last." - Kuronuma to Professor Miyajima after throwing him into the execution chamber
- "Stupid Earthlings." - Kuronuma, after believing the humans are killed by a car bomb
- "Godzilla is still alive. I guess we'll have to teach him another lesson. Mechagodzilla, beat Godzilla to death." - Kuronuma giving orders to Mechagodzilla after learning Godzilla survived their first battle
- "I can't believe it. Mechagodzilla, the magnificent machine, has been defeated." - Kuronuma, after Mechagodzilla is destroyed by Godzilla
- Kuronuma's line "Mechagodzilla, beat Godzilla to death" is repeated almost word-for-word by Rhizon, the commander of the Cryog aliens, in the comic series Godzilla: Rulers of Earth.
- Kuronuma's successor in the film Terror of Mechagodzilla, Mugal, is portrayed by the same actor, Goro Mutsumi, and therefore looks and sounds eerily identical to Kuronuma.