Cyberdramon (Cyber Sleuth)

Cyberdramon is Ryuji Mishima's Partner Digimon.

Digimon Story: Cyber Sleuth - Hacker's Memory (Manga)
When Keisuke Amasawa's, , and are fighting against the Dinosaurists Monochromon, Tyrannomon, and Triceramon, Ryuji Mishima, Chitose Imai, Erika Mishima and  arrive and Ryuji has his Cyberdramon help fight. They defeat the hackers, then force them to release all the Digimon they were keeping locked in cages.

Justimon


Justimon is the Mega form of Cyberdramon.

After Ryuji returns to his normal self, he stands in Ikebukuro and demands for all of the hackers to beat him up for what he had done. They refuse though, so he then demands for Cyberdramon to beat him up instead. At this point, Fei Wong Tomoe Ignacio and arrive and she states she will fight Ryuji to teach him a lesson, though he only needs to return to his old self to truly apologise. When he realises this is the truth, he decides to return to his old ways. This then leads to Cyberdramon digivolving into Justimon. Ryuji, Chitose Imai and Keisuke Amasawa then defeat Fei and two other hackers in a Domination Battle.