Yu-Gi-Oh!: Why Yami Yugi Is A TERRIFYING Monster
Though portrayed as a hero, Yami Yugi is actually incredibly sinister in the original Yu-Gi-Oh! manga.
Yami Yugi is one of the most important heroes of the original Yu-Gi-Oh! Duel Monsters series. When you think about it, though, all that "power of friendship" storytelling just puts a gloss over his more twisted actions. From an objective point of view, taking over a young boy's body is already kind of questionable, and his subsequent actions go far beyond just "questionable."
In the first episode of the anime, Yami Yugi uses Mind Crush on Kaiba immediately after defeating him, which supposedly sends off his evil side to the Shadow Realm. In the manga, though, Mind Crush is shown to have far more potent effects that leave the victim in a potentially permanent coma. It doesn't stop there: the "Penalty Games" that Yami Yugi uses in the manga paint him in a far more sinister light than the Duel Monsters anime does.
The Yu-Gi-Oh! manga is a lot darker than the censored 4Kids version, or even the uncensored Japanese anime. Spanning 38 volumes, it featured Yami Yugi often taking over Yugi's body to defeat numerous villains. Heroes are no stranger to abuse of power, and the Pharaoh certainly abused the power of the Millennium Pyramid. The Shadow Games were used to injure people with explosions, send a television producer mad and much worse. Though the victims committed evils, the punishment -- "poetic justice," as Yami Yugi calls it -- is often far too much. That punishment, according to Yami Yugi, is his definition of a "Penalty Game."
One particularly cruel punishment targeted the escaped prisoner Jiro. Incredibly thirsty and in want of alcohol and food, he quickly holds a restaurant hostage. Yami Yugi -- who happens to be in the restaurant -- challenges the villain to a game, and ends up literally setting him on fire (and almost assuredly kills him). Even the 1998 anime, which was far darker than the subsequent Duel Monsters anime which came over to the States, had to tone this down, making the fire merely an illusion.
Yami Yugi never had to actually set Jiro on fire in order to deescalate the situation -- he chose to. That willingness to make people suffer even though he doesn't need to is what makes him incredibly scary and, from a certain perspective, almost evil.
Yami Yugi finds his redemption later on. He never employs the Penalty Games after the Duelist Kingdom arc in both the anime and the manga, as he learns of kindness and mercy from his lighter (and shorter) counterpart. Though he eventually manages to beat his opponents without intimidation through Shadow Games or Penalty Games, it's hard to forget that he still retains a sadistic streak and the power to force his opponents into madness.