They're called Dekotora trucks, and people spend up to $100k building them.
Japan has its own way of doing things, such as art and cars. There are very interesting and unique results when those two elements are combined. One example are Dekotora trucks, which literally translates to "decoration truck." It's a pretty bland description because these trucks are outright nuts, putting it mildly. Originally built as dump trucks, people buy them and spend up to $100,000 turning them into an LED light display of ridiculousness.
Barcroft Cars has profiled one particular Dekotora truck that took more than 10 years and 100 LED lights to bring it to life. Turns out trucks like these are a fairly normal occurrence in Japan, so it's not totally uncommon to see one. Of course, they're merely hobbies for owners, and expensive ones at that.
They're not daily drivers because even crazy Japanese car tuners have common sense, but Dekotora trucks are respected. They appear regularly in TV shows, commercials, and other live events. They are literally drivable works of art with extravagant paint, stainless steel and even gold exterior elements, alongside the LEDs. And yes, they're typically street legal.