This is an old story that goes back many years, but hopefully you can help me out.

I think this goes back to 93 or 94, when I was a young kid of 8 years old. My friends were all into Akira, Fist of the North Star, but mainly Guyver. Totally obsessed with Guyver! Anyway one late night, i saw a commercial that they were putting some Manga on tv very late night (at 1am in the morning because it had adult content), so being the naughty kid that i was, i sneaked down to watch it. Now I dont remember much, but im sure what i do remember will be familiar to many. Here is the only part of the story i remember (although some of it may not be true, lol);

-There was a group of brothers, alot of them
-They rode bikes (possibly)..futuristic ones? (or am i just getting confused with Akira lol)
-One of the sub stories involved the story of the bad guys(well she was a girl) mother (grandmother). She was raped(or had sex) by an American soldier during the war & therefore was possibly abandoned by her mother. I remember this final point because it was a bit shocking to my then innocent mind lol.

Ive tried to find out for years what film this was, but to no luck. Could any of you help me out?