I was thinking, "I'll give this guy a butterfly theme, like how Kamen Rider has a grasshopper/bug theme." It's a little comical to see a crimefighter who has a theme not commonly associated with good/justice. So, basically, Kamen Rider, Spider-Man, Robin, etc.
I also thought about doing a "justice theme." In the top left, I have the guy with his eyes covered (as justice is blind), and a scale symbol on his chest. But, with his eyes covered, he wouldn't be able to emote as well, and he might look like some sort of blindfolded kung fu guy...
I also thought about incorporating the Japanese word for justice, seigi 正義 into his costume (or just the 正 part of it), but then to most people he would just look like some Asian-themed character, and they wouldn't understand the "justice" part.
Here is more on that justice theme. A western representation of justice is a blindfolded woman holding a sword and a pair of scales. I ended up with a somewhat knight-ish costume. Although, it seems too appropriate, and not silly enough. Somehow I think this kind of theme/motif would be good for a more serious take on a superhero, not a comical superhero... I'm confused here.
I had also thought of a police/riot-gear type costume, but he wouldn't look silly enough when trying to enforce his own brand of justice.