Let's take a moment to review that briefly: The main character's names are Mark, Tom, John, Jack, Jim, and Jane. No one seems to have a last name. Also, lead singer Tom is rocking an incredible mullet/mustache combo. Because that's the kind of movie Miami Connection is.
Anyway. Jane has had an especially hard life, which she spontaneously relays to John before changing the topic just as quickly.
John: Jane I've wondered about your family, do you have any family or anything? I haven't met anybody yet or...
Jane: Well, I have a brother. As a matter of fact and if it wasn't for him I wouldn't be going to this nice school and staying in the nice dorm room I'm staying in.
John: That's really nice of him.
Jane: Except for one thing... I don't really like him.
John: What? You don't like your own brother, why?
Jane: Well, I can't really explain it, I just don't like him.
John: What about your parents?
Jane: Well, they were divorced when I was young, my dad took off with some young girl and left my mom and brother and myself and she had to raise us all by herself. She had a tough life. And she... shortly after that died. And my father died a little while he left us. But speaking of my brother, I think it's time to go meet him.
The problem? Jane's brother Jeff is second-in-command of the motorcycle ninjas, and he doesn't want Jane hanging out with this band. He swoops in with his gang, parks in two handicapped spots, harasses Jane for singing at the club, then punches John in the face. You know, in case the cocaine deals weren't enough to make him the bad guy. It comes dangerously close to escalating into a full-blown brawl in the university parking lot when the rest of Dragon Sound shows up to hold them off. But now the band is on Jeff's radar, and he doesn't need much of an excuse to destroy them.
Lucky for him, that opportunity arrives when a musician who lost his gig to Dragon Sound approaches Jeff with a proposition: get rid of the band and he'll give Jeff his profits. I assume Jeff would normally ignore this because he's a freaking cocaine dealer who doesn't need washed up musician money, but now he's got a personal vendetta. What he didn't account for was Miami Connection occurs in a parallel dimension where everyone knows Taekwondo. At least three members of the band are black belts, the man who runs their favorite restaurant can take out anyone who refuses to pay the bill, and the freaking club owner has a martial arts fight for no reason in the middle of the movie. I assume this is why no one seems especially phased by ninja bikers: they're just a minor level up from everyone else.