He should be a playable character in SSB4 because he will replace Ike. Kirito is the main protagonist of Sword Art Online. He was a Beater during SAO. He is a skilled swordsman. Kirito's avatar had the appearance of a ridiculously handsome protagonist from some fantasy animation, looking older than he actually was.
Special: His special skill, where he uses his two swords which are Dark Repulser and Elucidator, and strikes the victim, similar to Link and Toon Link's special, except for the triforce included, and there are two swords.
Up B: He uses his sword as an extra jump
Left/Right B: He strikes his sword to the left/right/