Greenman vs. Iho Killer (グリーンマン対イホキラー, Gurīnman tai Ihokirā?) is the twenty-second episode of Go! Greenman.
The episode starts with Maoh scolding Tonchiki for constantly failing. In an effort to impress Maoh, Tonchiki suggests that they extract Greenman's power source. Maoh agrees, and Tonchiki leaves with a plan. He summons his own monster creation, Iho Killer, and the two trap the kids. But, they use their Greenman Calls to summon their hero.
Greenman appears to answer the call, and battles with Iho Killer. After quickly being beaten down, Iho Killer is grown by Tonchiki. Greenman wastes no time in growing, and almost immediately called out "Greenman Giant Machine Change!" which caused him to grow to Iho's size. The two battled in a small town. Iho began to overpower him, and Maoh instructed the monster to use his secret weapon. Iho Killer pulled a patch from his chest and threw it at Greenman. It stuck to the hero's body and began to slowly paralyze him. This caused a small red light on his chest to light up which indicated his electronics had been damaged. But, before the weapon could take full effect, Greenman managed to pull the patch off himself.
He attempted to use his Breaster attack, but his damaged electronics prevented the mechanism to work properly. Greenman had been so damaged, that it caused him to shrink back to human size. Tonchiki danced around the downed hero and kicked at him, but, he accidentally stepped on a Greenman Call that had been left by one of the kids. This repaired his machinery, and Greenman grew to finish off Iho Killer. After a thorough beat down, Greenman defeated the monster with a successful Breaster attack.
Iho was destroyed, Tonchiki was scolded, and Greenman flew off with the now safe children waving goodbye to him.