Kato can have any appearance due to his shape-shifting powers. However, he most often appears as a tall black fox with completely red eyes. He also likes to assume the shape of giant spiders and flowerpots.
He assumes the appearance of a black fox with red eyes much of the time to scare people. However, he doesn't do this for evil reasons. He wishes to keep others away from him so that they don't come up to him just to be captured by his alternate personality; Yona.
In the rare moments that Kato is alone, he transforms into a black fox with chocolate eyes, so as to assume a somewhat normal appearance.
No one knows what Kato's "true form" (what he was born as) is. Most likely, his appearance resembled a typical Etherling (like Abyssal The Etherling), tall with a large tail, and strange markings.
Kato has a severe mental disorder which gives him two separate personalities. He changes between these personalities randomly, and he often cannot stop the personality change.
Kato's original personality is named Kato. He is quiet and thoughtful. He feels like an outcast because of his sudden personality changes, and often feels lonely and hated. He currently loves Glacier the Cat, who does not return his affections. He is more of a neutral character.
However, Kato can also become very bitter, especially towards his father, who caused his disorder. He can get very upset about losing most of his friends after they find out about Yona, and will sometimes go into depressed stages where he isolates himself from everyone and quietly cries.
Sometimes Kato gets whiny, especially when trying to convince others that he isn't actually an evil sadist.
Yona is Kato's alternate, evil personality. He is sadistic and insensitive. He cares little for the feelings of others. He enjoys kidnapping girls and forcing them to kiss him and more. He will basically grab any girl he can get. Obviously, he's evil.
His origin is unknown, however, it is speculated that he is actually a highly sophisticated form of disease. (See Furi the Etherling's backstory for more info on Yona.)
(As Yona) "But I love you too much to let you go."
Unwell - Matchbox 20
Let Her Go - Passenger
Hurricane - Needtobreathe
Both of Kato's parents are still living. His father, Furi , is a prideful, ambitious king who injected Kato with the virus that became Yona to prevent him from being a threat to his throne. Fury is currently the tyrannical ruler of Kato's home planet. His mother, Kira, is a nice enough person, but she is simply a puppet in his father's hands.
Kato has seen Abyssal looking for him, but he believes that Abyssal is trying to bring him to Fury and as such, avoids him carefully.
Kato has quite a few powers. Etherlings are randomly born a certain Level, and their Level determines their powers. Kato is the highest level an Etherling can be, like his father. However, probably due to his father's meddling, Kato gets tired easily while using his powers, especially if he uses powers many times in succession, and may fall asleep at random times.
He can shape-shift at will. This makes him a bit tired, but not terribly.
He can read minds, although he cannot read the minds of others who are telepathic. He also has to put his hands on either side of the person's head when doing this. This makes him quite tired.
He can control minds, although he cannot control the minds of others who are telepathic. He also has to put his hands on either side of the person's head when doing this. This makes him very tired, and he cannot keep it up for more than a few minutes without falling asleep.
Kato has narcolepsy.
Kato is an artist, and likes to draw pictures in his spare time.