Ronin is a self-centered yet skilled ex-thief and bounty hunter. Formerly based in Stiix with his airship R.E.X., Ronin's made many mistakes; he made deals with the Soul Archer and even sold Zane to Master Chen. However, looking to change his ways, Ronin sided with the ninja and oversaw Nya as she tried to master her Element. Morro forced Ronin to steal the Sword of Sanctuary, and lead the ninja into a trap. They made amends, and Ronin helped them fight the Preeminent and an army of ghosts in Stiix.

After the Battle of Stiix, the Police Commissioner hired Ronin to capture the ninja due to crimes they committed, and he agreed (at least partly because of the money) though they were framed. When the conflict with the Sky Pirates escalated, Ronin joined Jay's rag-tag team and raided New Djinjago. Due to Jay's final wish, recent events were undone and Ronin never captured the ninja or joined Jay's team.

On the Day of the Departed, Ronin built himself a new mech and used it to help Jay defeat a resurrected Samukai.

Sometime in-between the Day of the Departed and the return of Acronix, Ronin opened up a pawn shop in Ninjago City and was injured while briefly aiding the ninja in the fight against the Time Twins and their Vermillion Army.

During Lord Garmadon's reign, Ronin was arrested and imprisoned in Kryptarium Prison. After he and The Resistance broke free, they helped destroy the Colossus and defeat the Sons of Garmadon.