About 1/3 of the way down this page (in Japanese sorry, but lots of photos) is a poster for a violin concert featuring Viohazard's teacher's first pupil, now a professional performer (...and right below that is a picture of people at the autumn festival, featuring yours truly and husband, if you know where to look!).
But RIGHT down the bottom, about 3/4 of the way down is a picture of kids
playing on a small outdoor stage at a local festival. It's the photo below two men playing shamisen (a kind of banjo) in traditional costume. You can see that all the kids are extremely casually dressed. That was at least 5 years ago, and most of the kids seem to be *a lot* more dressed up these days.
Recently Viohazard is quite taken with those colorful Eastern European/Russian/South American peasant shirts with small amounts of braid trim or embroidery. Sounds like good busking/casual solo wear to me...as long as he's prepared to do the embroidery!
He's all for wearing one of the historical Japanese costumes like "samurai period" ones the shamisen players are wearing...but I think a violin would get lost in the costume

! Darn it, what's wrong with a guy playing violin in the New Zealand national costume of black wool singlet, baggy khaki shorts, and black gumboots? - plenty of movement, practically monotone black, and if the music isn't up to scratch, there's always the rippling biceps and hairy legs to gaze at!!