J-Rex is the creature that was made by robotic substances and hybridised with a shark. It appeared as the servant of Tengkotak team. After Bora Ra directed Yoyo Oo to release J-Rex, it was released by Yoyo Oo and J-Rex was seen running to outside.
Meanwhile, Adu Du and Probe tried to deceive Papa Zola with lying by saying BoBoiBoy and his friends were captured by Tengkotak. However, the appearance of J-Rex behind Papa Zola suddenly shocked three of them, then they ran away from it. Due to the high speed, they did not realise that they had exceeded the ravine and immediately fell. Therefore, they rolled until arrived at the end of the ravine. Fortunately every of them managed to hold on the rocks to prevent them from falling down. However, the higher ravine made Papa Zola very shocked as he was the lowermost.
Then, Adu Du asked Probe to pull them upwards. Meanwhile, J-Rex was still chasing them. However, it slipped and realised that it would fall into the ravine. While Adu Du waving to J-Rex, suddenly it stopped from falling. Apparently, Papa Zola had saved J-Rex withholding its leg. Said Papa Zola, the justice will never allow whoever from falling. Therefore, they got a new friend, J-Rex which was vicious became tame because of Papa Zola with its new name; Justice Tame Shark!
- The name of "J-Rex" is a pun of "T-Rex", the kind of Dinosaur. However, its name means "Jerung Rex", and Jerung means 'shark' in Malaysian.