Once-loved brothers, Shikaku and Gain used to work together as ninja assassins, doing their master’s commands without question. However, one day, the brothers had a falling out, and their relationship became strained. Gain had a sense of morality and righteousness, while Shikaku had become cold and apathetic. Their differences made them clash, and soon, they were sworn enemies. Shikaku then turned to corruption and darkness, using his mastery of water skills to cause devastation and destruction.