I have not even a passing interest, however...
As a small child, I did like Astro-Boy, especially the squeeky sound of his footsteps. Later on, you had Marine Boy and then Speed Racer. But my favorite Japanese cartoon of all time was rather obscure, as nobody today seems to remember it. Eighth Man, from the sixties, and in black and white. He was a robot (The Japanese were big on robots on those days) that had a big 8 on his chest, and a smooth helmet on his head. He wasn't huge like Gigantor or Ultraman, just normal human size. To me he looked like a football player. His powers were pretty much as you'd suspect, superhuman strength and invulnerability, plus he could fly, I think. In my opinion though, his coolest skill was the ability to assume the guise of anybody he wanted, in an instant. For the most part he was either himself or his alter-ego, Detective Tobor. Yes that's robot spelled backwards. Tobor had a secretary named Jenny Heartsweet. The only other recurring character was Professor Genius, Eighth Man's creator. The music was kind of cool, too...
Call Tobooorr...The Eighth Man!...
Toboooorr...The Eighth Man!....
Faster than a rocket...
Swifter than a jet...
He's the mighty robot...
He's the one to get...