Strikeman is what passes for a
villian in the "
You're Under Arrest!"
manga. He is, as far as I know, not present in the
anime, at least the the
OAVs.
He's not so much a villian per se, as a vigilante - I've heard Strikeman described in D&D terms as chaotic good, and that sounds about right. He has a really strange costume that resembles a baseball uniform, with lots of outlandish embellishments like a mask and feathers. Yes, feathers. Rather than fighting real crime, he tends to punish things like parking violations, public urination (not uncommon by drunk salarymen in Japan), and other such trivial offenses by using forces of justice like "The STRIKE DRIVER!" (he lets the air out of the offending car's tires). Stuff like this drives the Bokutou police force nuts.
He actually does have a really good fastball, and when Natsumi succeeds in hitting it, he's astonished, and gives her the name "Home Run Girl", which annoys Natsumi no end.
I would love to do a Strikeman costume, but one really needs to be well over 6 feet to pull it off, because Strikeman's a really big guy.