Rocco is an inhabitant of the town of Ruan.
He's one of the leaders of the Raven gang who hangs out in the warehouse district near the city docks and occasionally causes trouble there. He and his fellow Raven head honchos run into Estelle, Joshua and Kloe who are exploring the city's southern district. Attracted to Estelle and Kloe, Rocco and his buddies start hitting on them and start threatening Joshua. Unfazed by Estelle's protests and Joshua's warning, the Ravens threaten to start a fight, but the situation is deescalated when Mayor Dalmore and Steward Gilbert arrive, threaten to call the bracers on them and Estelle and Joshua reveal that they are bracers themselves. Reminded by Deen that the three of them picked a fight with a lone female bracer before and got soundly beaten despite the advantage in numbers, the three of them decide not to press their luck and leave.
When Clem comes storming into the gang's warehouse the next day and starts shouting at the Ravens, the gang threatens to beat him up, but they're interrupted by the timely arrival of Estelle, Joshua and Kloe. This time, Rocco and the others engage the bracers in battle, although in the end they're soundly beaten. The standoff continues, even after the battle, until Agate turns up and reasserts his authority over the Ravens by badly beating up Rocco after the latter tells him they're not going to listen to a former member who walked away from their gang.
After or during the school festival, the mayor's steward Gilbert apparantly visits their hideout, but Rocco can't remember what happened next. He and the other Ravens are controlled and Rocco and two others are made to guard the third floor of the lighthouse where they're defeated once more by Estelle, Joshua, Kloe and Agate, although they put up a much tougher fight than before. After being beaten yet again, they're locked in Manoria's windmill shed until the army arrives. Since it's decided that they were being controlled, they aren't taken to Leiston Fortress and return to Ruan instead.
After Estelle and Joshua travel to Zeiss, Rocco and the rest of the Ravens engage in some training and eventually enroll in the martial arts competition taking place in Grancel. Rocco, Deen, Rais and one of their buddies even manage make it to the first round of the finals where they're pitted against Estelle, Joshua, Zane and Olivier. Eager to exchange some trash-talk before the match, Rocco and his buddies head over to the other waiting room to confront their opponents, but Estelle's unexpectedly high-spirited attitude flusters them to such a degree that they end up quietly walking away.
Their winning streak from the prelims doesn't hold up though and they end up losing to Estelle's team. As a sign of good sportsmanship, however, Rais, Deen and Rocco give Estelle the key to one of the sewer areas beneath the city, which they acquired by chance, so she and the rest of her team can train for the matches ahead. Afterwards, they presumably return to Ruan without sticking around until the end of the competition.
According to his combat information blurb, Rocco's nicknamed "Nitro" for his quick temper. He is indeed the most impulsive and hot-tempered one among the three gang leaders and the one least likely to think before acting or talking. This comes back to bite him when Agate visits the gang's hideout and starts scolding them for their behavior. Rocco angrily tells Agate to shut up since he's no longer in a position to give orders, to which Agate responds with an uppercut that packs enough punch to send Rocco flying into a nearby wall. Rocco later admits he was sincerely terrified that Agate was going to kill him.