Off the top of my head, I’d say manga/anime/live-action henshin (“transform”) heroes like Ultraman, Kamen Rider, and Kikaider probably fit the bill for Japanese super-heroes. But there’s a lot of differences there still. Someone else should talk about them because I’m not very knowledgeable about that style.
Additionally, one could point out the fantasy martial-arts shows like Inuyasha, Dragonball, Bleach, Naruto, and say that these are Japan’s super heroes. Tthey certainly all seem to reuse animation over and over, have mid-fight introspective recaps, talk extensively about the character’s relative power levels and the need to power up, or learn that one new super-move. They also typically have a dumb, headstrong male lead character.
This bears some clarification:
Mecha’s a western term, as I understand it, the Japanese genre terminology translates into:
“Realistic Robo” - shows/comics like Gundam, Macross (one of several anime edited to make the north american cartoon, “Robotech”), Patlabor, etc. These works generally try to have a certain level of believability and realism to the machinery, and are usually epic sci-fi war-stories or something to that effect.
“Super Robo” - shows like Mazinger Z (“Tranzor Z” in north america), Giant Robo, Getter Robo, the Brave series (including GaoGaiGar). These usually have a teenager or small child (usually a boy) who either directly pilots, or orders around, a superpowered robot. These shows emphasise style over plausibility, and are usually very cartoonish and over-the-top (to the point that they are often lumped together as childish, although not every series is; eg. Big O, Gurren Lagann, or Evangelion*)
Then there’s “Sentai” shows, like Voltron or Power Rangers (and it should be noted, the North American “power rangers” is a composite of many different live action sentai series, with new sequences shot for english audiences, hence the constant re-invention of the machines and enemies). Groups of people (usually all teens) who fight in colorful uniforms (often with magical or fantastical abilities) and then pilot themed machines that link together to form a humaoid robot to have a godzilla style battle at the end.
*Some shows blur the lines to one extent or another; G Gundam, essentially a satire of Gundam and Street Fighter type games, is definitely more Super Robo than anything else. Other shows like Evangelion don’t really fit any format easily (the mechanics of Eva are largely super, but the tone and story-telling are way outside the norm for such a show).
Gundam Wing, among other things has very little actual technobabble for a realistic robo show, and some prety over-the-top powers, not to mention the sentai-like 5-gundam group and their highly one-dimensional pilotss and clearly delineated abilities and color schemes.