Yurie, the princess of Asronia, is kidnapped on her way to a celebration in the kingdom of Gostaria by the dragon forces of the Demon Dragon King. Yurie's bodyguard, Maya, survives the attack, and has vowed to rescue Yurie no matter the cost. Until then, Yurie must endure the Demon Dragon King's sexual Depravations.
When the Demon Dragon King appears, he looks and sounds like the fantasy version of Darth Vader, breathing problems and all. And to top it all off, his helmet has giant blades coming off of it. It's dumb, but awesome. But the real kicker? He's not actually a giant warrior, but a regular sized guy who just happens to walk around in a giant mecha suit. I don't know how he got it or where it came from. Maybe he's a time traveler who came back in time to conquer every kingdom, or he's from a completely different planet, and he's using high advanced technology to take over, or even that this world has the capability to have this technology, but in very limited quantities. I'll never know. Well, that's my head cannon at least.
A lot of other things go unexplained too. One of the The princesses guards is a ninja apparently, and can use some form of magic. I don't know if other guards are like her, or if she's just been trained this way specifically because she's the princesses guard. Some characters and plot points are also brought up and just as quickly forgotten. It's like the script writers had ideas, but not enough to fill out a proper plot. I tried my best to see if I could find out of this is based on some old PC-98 game obscure manga, but I couldn't find any evidence of something that this is based on to explain why some plot might not be here.
Probably the most memorable character is a sexy dominatrix that works for the Demon Dragon King, not only because she's the only thing that actually stands in terms of character design, but she actually gets some backstory. The only other character that I liked was the super powered ninja guard who tries to save the princess, if only because she had some actual character. Unfortunately, the anime ends before any of the story gets resolved, so all we're left with is some metaphorical blue balls.
Would I recommend Erotic Torture Chamber (AKA Princess Road: Bara to Dokuro no Monshou)? It's a bit bland considering some of the hentai we have these days, but in terms of old hentai, it's actually quite amusing.