Unfairy is noticeably shorter than the other Wicked Executives. He has a pudgy body with gray-white skin, thin arms and short legs, and two fuchsia dot-like eyes with buckteeth, as well as two horn-like protusions on top of his head. Like most of his colleagues, he has the same color scheme of clothing as them, in particular his being an oriental top colored dark purple with milky pink linings and the trademark hot colored Wicked flame in the center. He also wears milky pink wristbands.
He was stronger than them but they got to sap his strength and stall long enough for Nate to get enough strength to beat him. After he is beaten and returned to Dedtime, he was thought of as weak and got sent away.
This shows Unfairy's stat on level: 99.
His Japanese name, "Yakkai" is a pun on "yakkai" (Japanese: 厄介,"troublesome" or "bothersome"), with the latter kanji being replaced by "kai" (Japanese: 怪,"mysterious" or "strange"), which is a part of all Wicked Executives and Wicked Servants' names in Japanese.
His English name, "Unfairy" is taken from the English words "unfair" and "fairy", and notably starts with "Un-", like all Wicked Executives' names in English.
His Spanish name, "Injustio", is a corruption of "injusto" ("unfair").
His German name, "Nervo", taken from "nerven" ("to annoy").