Ken Yoshzimaru (吉丸健)is a Former Antagonist player from Sword Art Online and now he's a Protagonist from Sword Art Online when teaming up with Floyd in the ALO and GGO.
In Real Life, Ken Yoshzimaru was an idiotic person to think that he's the best of all players and is the best against Floyd. He was a nice guy to Floyd of thinking too much of thinking to become a hero and he knows what Floyd said to him makes him change.
In SAO, Ken is still an idiot to think that he's a best of all but he knows that he's was trying to get their attention but he notices that everybody calls him an idiot loser and he grow over his hatred and start to attack the other players and start fighting against Floyd again. After that in ALO, he turns out to become a good guy to own Floyd his life for about friendship is stronger than strength.
In Real Life, Ken has light-skin, white hair, wears like a Ghoul suited coat and shirt, has a light brown eye, and he's a total idiot with an idiotic mood.
In SAO, Ken was wearing a brown knight suit that some sort like a demon-like, his face lines and arms are bluish-green and his body is brown, his belt.and has katanas on his back and a special weapon on his hip.
In ALO, Ken's skin is dark bluish-purple to go through the shadows of darkness, two katana were placed on his hip and back, has pointed elf ears, wears a ninja suit to hide in the shadows to steal treasures and make illusions, has the white eye and bluish-purple hair.
In GGO, Ken wears a black and white assassin suit with the X symbol belt, wear a ninja assassin mask, and wears the white sleeveless cloak coat to hide his identity from the other players.
In OS, Ken wears a Demonic armor suit, wear a black cape, Demonic scale armor, two pointed horn Demonic Mask, Yellow Markings on Ken Mask to represent his eye on his mask, Demonic Armor claws, and His Body is covered in Demonic Armor.
In PA, Ken is now the form of a purple demon. This is his basic form and the easiest form for him to reach. Ken gains an "oni face" which is a crest that forms on his forehead. When transforming into an armored simply change colors, the armor equipment effects here are much greater to fuse with him, each becoming armored for his form. Finally, his oni face is covered with a samurai-like shield and his horns expand a bit.