He is the honourable Shuutarou Mendou. Scion of the richest family on the planet, descended of the samurai cast. Shuutarou is heir to the 4 trillion dollar Mendou Conglomerate. His family owns much of Japan as well as chunks of many other countries. They are a militaristic government on their own. They have their own secret police, and even more spectacular is their highly advanced and powerful private army that could very well blow away the Japanese army if need be.

Mendou tries to live his life by the codes of bushido. He is well-bred, stylish, talented, athletic, handsome, chivalrous, disciplined, intelligent and wealthy. In short, he's everything the girls go crazy for...especially the part about money. Pretty much all females who don't know any better find him irresistible and Mendou doesn't do anything to discourage them either. He is an exceptionally active womanizer. He'll hit on just about any woman he sees. Mendou treats all women like they are goddesses, but similarly he treats men like garbage.

Mendou first arrived suddenly one day as a new student at Tomobiki High School parachuted from one of the Mendou private heavy bombers. Mendou who has no tolerance for idiots or ugliness immediately became rivals with our protagonist, Ataru Moroboshi. Mendou could easily have just about any woman he wants but he just leads them on. The only woman he truly wants is Lum. Suffice it to say, Lum's not interested since she is completely faithful to Ataru. This is the greatest factor in contributing to Mendou's enmity towards Ataru. Still even though he has power, honour and good looks, most of the time, Ataru can still get the upper hand over Mendou.

Without his power or genteel manners Mendou is more like Ataru than he'd readily acknowledge. Not the least of which that they have two of the biggest libidos in Japan. They always compete over women. Of course Mendou goes about it with far more tact than Moroboshi, but that's not always the case. As time passes Mendou turns out to be just as much of an idiot as Ataru.

Mendou's greatest fault is his pride. On the surface he seems to be as close to perfection as possible and he knows it. He's really full of himself. That being the case, it's easy to anger him with nothing more than a quick insult. When his honor is offended or if given the slightest provocation, he whips out his ancient katana with the intention to kill. In more dire moments he'll dispatch his army to fight his private battles.

Mendou has an acute fear of the dark and of cramped spaces. Any one of those things can cause him to go uncontrollably mad with fear. But staying true to his vain nature, this fear is nullified whenever he sees that a woman is present. Ataru loves to use this to bring Mendou down off his high horse by encasing him in a large shrine bell trapping Mendou in a terrified panic. While he's usually a pathetic, cowardly figure at such times, he sometimes becomes momentarily psychotic and goes completely berserk. Enough to rip through a thick solid steel encasement. It so happens that when Shuutarou was a child, a future version of himself caused his phobia to emerge.

As an added note, the symbol of Mendou is the octopus. The family crest is an octopus face, much like those on festival masks. The octopus is his biggest hobby and he has a large number of octopi as loyal pets.

Mendou's orders are followed out by his personal retainers who all wear black shades and look highly professional. But despite their looks, they are all good-for-nothing incompetents. Mendou still has to do everything for himself.

He has a lot to deal with in his life. The fate of trillions rests on his head, but Mendou biggest troubles are with the people he deals with daily. His insane parents, his sadistic sister who delights in torturing him, a bodyguard who is more dangerous to him than helpful, a girl who outdoes him at charming women, a fiance that could either kill him in fear or crush his spine with a single hug, and most of all his biggest enemy, Ataru Moroboshi who stands in the way of his happiness. Still he and Ataru do become best friends, even though neither of them would ever admit to that. It's still a very destructive kind of friendship.