The name Yoru (Kanji: 夜) is Japanese for "night." His abilities were inspired by ferrofluid, a type of liquid that is attracted to magnetic poles. His mask came from the Edo period. Only Yoru is able to utilize the powers of his mask. His voice actor, Daisuke Takahashi, also voices Yoru in the Japanese dub. Yoru collects knives as a hobby.