Mentor Ji is the Samurai Rangers' master and trainer. He also seems to be Jayden's legal guardian. He is very strict, but worries about the Rangers. He and the Red Ranger both have a secret that they keep from the others. He is the one who gives the rangers their morphers except for Antonio's, who built his own, and from whom he confiscated it, only to return it in the same episode.
Mentor Ji has been a part of the Shiba House since Jayden's father was the Red Ranger and is presumably Jayden's guardian. Ji has trained Jayden after Master Xandred's defeat at Jayden's father, which brings questions to light of what happened with Jayden's father after he sealed Xandred away and what his relationship with Jayden's family is.
In The Team Unites, Ji is show helping the rangers train before they are sent to fight Rofer.
In Deal with a Nighlok, Ji gives the ranger information on Doubletone.
In Day Off, Ji gives the rangers a day off from training, but Jayden chooses to continue; he watches over Jayden's attempt to master the Bettle Disk and expresses concern on Jayden's condition after training himself to near exhaustion all night, remembering when Jayden would train the same way as a child but would let himself have fun.