Zoruru is a very cold (some could say hearted) keronian. He kills without a second thought. Not many people are sure what happened to make him as such but all that is known is that he is not someone to sniff at. Zoruru is a very powerful assasin.
Zoruru is a cyborg Keronian. The entire left side of his body is all metal, his left hand having a retractable blade, and his right side body color is gray. His eye color is black with red irises. Zoruru's symbol is a three-pronged shuriken, and he wears a cap with his symbol on it over ripped cloth on his head like Dororo. In episode 336, his child appearance is shown. He still has the gray skin and but both eyes, which are the same as Keroro's, are shown along with both sides of his body. He wears a yellow cap with his symbol on it and his mouth is also shown.
Not many people know exactly what happened to make Zoruru half metal. One rumor is that during a mission with Dororo (Known as Zeroro back then) Zoruru was caught in some sort of trap of some sort whick caused him to get trapped, half of his body lodged under something and that Dororo, in shock and frightened went to get help for Zoruru, promising to return. But Dororo never did return. (which is why it is rumored that Zoruru hates him so much).
A question on that note is: Well if it was so traumatic for Dororo then how did Dororo forget Zoruru? There is a rumor to answer that too. Dororo was perhaps brainwashed of the event by the military so that he could still fight and be a soldier efficiantly, because Dororo is such a highly skilled assasin (Obviously treasured). Perhaps that is the reason Dororo forgot. Not of his choice but forced. And not because he didn't care, but because he cared so much it broke him to the point of not being able to function.
Dororo - Dororo is Zoruru's reason for revenge. In episode 103, it was revealed that they met sometime in the past (Dororo was then Zeroro). Zoruru still calls him Zeroro in that episode. Upon meeting Dororo he says, "Before I was once your... no." Later it is revealed that he was part of Dororo's assassin troop, led by Jirara. In a flash back, he can be seen sparring with Dororo in the rain. Zoruru has unfinished business with Dororo. It appears somehow he is responsible for causing half of Zoruru's body to be replaced by machine. However, upon meeting with Dororo (formerly Zeroro), Dororo had absolutely no memory of him. This in turn caused Zoruru to go into severe depression instead of proceeding on with his revenge. It appears like Dororo, Zoruru is easily depressed and will lose any will to do anything in turn. Like Dororo this could be called mope mode. The fact that Zoruru was forgotten by Dororo is an irony, as Dororo is often forgotten by his own team mates. Zoruru is apparently a very effective and skilled killer, as he fought and easily defeated Koyuki despite her ninja skills.Edit
Garuru - Garuru is Zoruru leader.
Tororo - fans of Zoruru and Tororo they like to say that Tororo act like Zoruru is his dad and Zoruru take care of Tororo.