This was a ride!
One thing that bothers me though...
There were hundreds of "highschoolers" fighting in many streets of a rather big town during the night - akin to a riot I would say - and not a single inhabitant woke up or reacted to what was happening?
I guess they knew of the danger and were scared, but still... Nobody called the police. Or did the police witness this offscreen and went "Nope"?
Well, you might come up with several explanations: Most of the fighting seem to have taken place in commercial areas, away from residential spaces. It's also possible that, because there are five different high schools clashing with surprising frequency, most people are just used to it (a less charitable reading might be, scared shitless), and although the scale of this recent battle is greater than usual and outside the norm, it's not concentrated in only one place so maybe most of the people thought it was a typical brawl. The police may have been called in but stayed out of the fight because that's hundreds of high-schoolers beating the shit out of each other and they cops may be overwhelmed. In the 80s and 90s, Japanese police was usually insufficient to deal with groups like bōsōzoku so it's not out of the realm of possibility.
But for the most part, it's rule of drama: If the police broke the fight up, you can't have the awesome brawls we have seen.