"DIVER #2100" by R.A.M. (Dennou Boukenki Webdiver OP1)
Boy, I am starting this half with an obscure-as-hell song from an even more obscure mech anime, aren't I? From what I can find out, Dennou Boukenki/Electric Brain Adventure Record Webdiver was a 2001-2002 series produced by Takara with animation by Radix & Nippon Animation. Supposedly it was created in a similar fashion to that of the Brave Series, i.e. it had a toy line to go with it, and just by looking at the OP you do get a slightly similar feel. Oddly enough, even though the show seems to have a water theme to it, it's actually about entering a futuristic computer network to battle a dangerous computer virus that has infected all of the "Web Knights" that protect the network; the water theme just seems to be how the robots are cockpit-ed. The only one to escape infection is Gladion, who teams with fourth grader "Web Diver" Kento Yuuki. So why do I include this song in the list?