In Japanese 正義 or 公正 can mean "justice" or "righteous" although 公正 carries the connotation of "fairness" (e.g.: 公正取引 (fair trade)). Being "righteous" or "just" are kinda the same thing. Heroic Autobots are called 「正義のサイバトロン」 (Righteous Cybertrons) and G2 Hero Prime's Japanese box has the words "Prime of Justice" written on it in English (with "justice" presumably being a translation of "正義").

From dictionary.com:
justice
noun the quality of being just; righteousness, equitableness, or moral rightness
righteousness
noun the quality or state of being just or rightful