Yellow Magic Orchestra (YMO) was the coolest Japanese synth band of all times. Extremely underrated for what they composed and the time at which they composed the songs. They were really ahead of their time. Their best songs included Rydeen, Technopolis, Multiplies, Behind The Mask, Ballet, and Solid State Survivor. From YMO came a bunch of Japanese bands that were heavily influenced by their sound.
There was another band from Japan that doesn't get mentioned a lot which sounds at times like Depeche Mode or Camouflage. I'm not kidding with the comparison. The band's name is SOFT BALLET. I think the reason they never got any attention was they sung all their songs in Japanese. If they would have tried to do an English album, I'm sure that would have caught people's ears.