The Rivalry of Takeru and Kiros
Maskman has a lot of great plot elements in it... although Takeru does seem to hog most attention considering the fact he has two major rivals namely Igam and Kiros. While his rivalry with Igam was based on honor killing, Kiros was one dishonorable bastard and here's what's the big deal about them. This guy's rivalry with Takeru was something that just got from bad to worse for the hero until its conclusion.
Where do I start? It's revealed in episode 27 where the villain first appears, Kiros is in love with Princess Ial and Takeru has NO IDEA that Mio is actually Princess Ial. Kiros has a habit of collecting treasures but somehow, he decided he must have Ial because he finds her extraordinarily gorgeous (which may explain why he hasn't flirted with other girls). Kiros though working independently, requests Zeba that if he can defeat the Maskmen, he will have Princess Ial. Which becomes a real plot driver towads the next episode.
In episode 28, a bizarre love triangle is made. Here Takeru is the selfless love type while Kiros represents a burning lust. After Kiros launches his attack, he plans to lure Takeru out to kill him. In their battle, he finds the necklace of Princess Ial in Takeru's hands. Oh boy, this gets worse when Baraba reveals to Takeru the truth about Mio while the battle happens. The result is that Kiros has a better motivation to kill the Maskmen, especially Takeru. Takeru is what Kiros believes stands in his way for his motivation with Ial. It gives him motivation to hate Red Mask EVEN MORE because he believes if he defeats Takeru, he will get Ial. But even if he does, she hates him anyway.
In episode 33, Kiros manipulates a girl named Eri to that end. Which she gets involved because she thought Kiros loves her which he doesn't. She mistook Kiros killing a monster to an act of saving her. This of course reveals how Kiros can be a manipulative bastard to use somebody in his scheme to get rid of Takeru. Oh all for his lust for Ial no doubt.
So really, the rivalry gets more intense when Baraba and not only Ial gets rolled into it. I was thinking when Zeba sentenced Baraba to death, it was presumably because Baraba knew of Zeba's dark secret. Moving on, Kiros decided it was time to get what he wants. He lured Baraba into getting Ia's ice coffin, use it as bait and revealed later he wanted to kill both Takeru and Baraba together just so he could get what he wanted. This of course, was a despicable act. Takeru kills Baraba but the real intense rivalry was between Takeru and Kiros.
The rivalry was concluded in episode 49 when Kiros met his karmic end when his own greed killed him. Takeru went to rescue Ial which he had gotten crazier. In that episode, he forces Oyobur to melt the ice coffin that encased his "beloved" Ial. The contrast between him and Takeru was shown- Kiros only viewed Ial as a trophy to be won, Takeru genuinely loved Ial to the point he let her go in the series finale. When Igam attempted to finally kill Ial, this led to Kiros being severely wounded. First Kiros was wounded by a sword then he was wounded by a huge icicle. He was soon dying, seeing what he wanted at the hands of his rival, stating he never got Ial.