Overview
Cassio Rollex is a Deputy Arena Master of Iia's Arena, sharing the role with Maple Manybell. He has a cowboy-like appearance (holster, chaps, the whole look) and frequently boasts about having defeated the Arena Master Jalily. The thing is, it's all talk. The game is upfront about this: Cassio talks a big game but has apparently never beaten Jalily.
Personality
Cassio is a braggart with more confidence than his record justifies. He positions himself as a tough, capable fighter, but the gap between his self-image and reality is played for comedy. Despite this, he does hold the Deputy Arena Master title, which means he's competent enough to have earned the rank. He just isn't as good as he claims to be.
Role in gameplay
Like Maple, Cassio is a Kardia character whose exclusive equipment unlocks at Level 21 for free. He's one of the early Nexus Battle leaders the player can use, and his cowboy aesthetic gives him a distinct visual identity on the battlefield. His specific Laws and combat bonuses haven't been detailed.