By virtue of being a silvery beetle, probably B-Fighter Kuwaga. None of the Metal Heroes really had the trademark rider bug eyes....for obvious reasons, but still. That's the closest match I can think of, appearance-wise.
So, I got through ep 6 of Agito, which is Gills's formal debut. I'm looking forward to watching Ryou's struggle, it looks like a great character arc. Hikawa gets some background, apparently he saved everybody on a sinking ship except one person, and the police want to cover that up. Hmm, I wonder who that one person was? (it's hilarious when Toei thinks they're being subtle) Ryou's girlfriend was a ridiculously wooden actor and I'm honestly glad she's gone. Shouichi is pretty interesting when he's not trying to be all innocent and fun. When an Unknown appears and he has to struggle with becoming Agito, we see the real Shouichi, and that's cool.
How long until G3-X?