Jei

Jei (or Jei-san), aka The Blade of the Gods, is a recurring antagonist in the Usagi Yojimbo comic series. He a virtually immortal samurai warrior who believes that he is an emissary of the Gods sent to purge the world of sinners, however, he sees everyone around him as a sinner and therefor kills anyone who gets his attention. He is the arch-nemesis of Miyamoto Usagi.

In the 2012 Teenage Mutant Ninja Turtles series, he is voiced by Keone Young.

Yojimbo
In the beginning of the episode, Jei is shown fighting with Miyamoto Usagi, who is enraged at him for murdering an innocent family. However, Jei claims that the family was infected with evil and that it is his job to purge the world of evil souls. As they continue to fight, Jei introduces himself as "the blade of the Gods" and prepares to kill Usagi, however, he is struck by a bolt of lighting and destroyed.

Later, Jei is shown to have somehow survived his previous encounters with Usagi, and, upon viewing his enemy with Kintaro, a child prophesied to have great powers, he summons four warriors to destroy Usagi. However, to his confusion, the warriors Jei summons end up being the Ninja Turtles. Deciding to use the Turtles, Jei poses as an injured old man and claims that Usagi had attacked him, getting close enough to brainwash the Turtles into becoming his soldiers. Jei, with the Turtles under his control, then tells them to kill Miyamoto Usagi, but leave Kintaro unharmed.

Powers and Abilities

 * Combat Proficiency: Jei is an immensely capable and powerful warrior. In one particular instance instance, Jei slaughtered an entire group of heavily armed ronin warriors without any weapons at all. Jei is also notable for being so tough that even his arch-enemy Miyamoto Usagi has a hard time keeping up with him, resulting in Jei having nearly killed him on multiple occasions.
 * Immortality: His most notable ability, Jei is shown to be immortal on various occasions, having been struck by lightning, fallen off a cliff and even sliced in half by a holy blade, yet still managing to return in one form or another.
 * Possession: As shown on different occasions, if he is killed, Jei's spirit can posses another person's body and use them to continue his legacy, although this possession can be undone by an exorcism.
 * Consecration: Jei can turn any weapon he collects or touches black to match his soul. After doing this to a weapon, Jei can use said weapon to steal the soul of anyone he strikes.
 * Mind Control: In the 2012 Teenage Mutant Ninja Turtles series exclusively, Jei has the ability to brainwash anyone he gets close to into becoming his loyal soldiers, although, if he desires them to complete a task, he must tell them it before brainwashing them.

Trivia

 * Jei has appeared in 47 Usagi Yojimbo stories, making him the series' most recurring antagonist.
 * Additionally, Jei has made more crossover appearances than any other Usagi Yojimbo villain, appearing in both IDW's TMNT comics and the 2012 Nickelodeon series.
 * Because of this, Jei is more of a nemesis to Usagi than Lord Hikiji, the main antagonist overall.
 * Throughout the Usagi Yojimbo series, it is never made clear whether or not Jei is actually telling the truth about being an emissary of the Gods, albeit a corrupt one, although is also suggested that he is really a Demon who possessed a priest (explaining why he can posses others if he is killed) or is simply an insane warrior.
 * In the 2012 series, Jei's "death" by lightning implies that, ironically, the Gods themselves view him as an evil soul and tried to kill him.