To start off with, I must say that Japan is a very sci-fi oriented society. Give them anything, and they can turn it into a good story of superheroes with amazing power fighting against monsters which when killed, will turn humongous to destroy buildings and roads, which seem to be rebuilt almost instantaneously after every chaotic fight. The good guys will call their own vehicles / animals / dinosaurs / aircrafts etc and transform them into a giant robot which will ultimately destroy the villain, almost all the time with a sword. Trust me, I've been watching the Super Sentai/Power Rangers series for around 8 years now, the sci-fi tradition never really change much.
Fans of Spiderman should be honored that their hero has a 'Japanese version' as well, called "Toei no Supaidâ-Man". Produced by Toei in 1978, Spiderman is a 41-Epidose TV series featuring Spiderman fighting an evil alien army lead by Professor Monster (so that you'll know he's evil just by looking at his name). So, instead of Green Goblin, Doctor Octopus, Venom, and Carnage, Spiderman has a more constant villain to focus on every week. The cool thing is, Spidey can get his red and blue suit from a magical bracelet, so he doesn't have to visit the loo when evil is near. As usual, Professor Monster will produce a super monster weekly to try to defeat Spiderman, and when killed, turn huge, and Spiderman will have to call upon his mighty leopard-headed aircraft Leopardon (duh~) for help. Apparently the Japanese think that spiders and leopards work well together. Leopardon can transform into a giant robot, and would use his sword to destroy the bad guy five minutes before the show ends. Read more about the series on IMDB.
Spiderman in action! Image from Sentain Base, a Russian site which quite some images of the Japanese Spiderman
The Japanese Spiderman series must be quite famous that Bandai actually include it into the Chogokin franchise. Chogokin toys are very exclusive, usually made from die-cast metal and hard plastic with metal coating. So, don't ever think that the Japanese Spiderman series is a fraud. Although it's laughable for people who watch Peter Parker all the time, different producers may work creativity in alternate ways, most suited to the favor and acceptance of the viewers. Take Power Rangers for example, the Western version has more action, and the Japanese version has more humor and teamwork (and cuter girls too ^o^), even though all their costumes and mecha are the same.
Anyway, the Japanese Spiderman is considered something in the past (made before I was even born). Right now, the Japanese entertainment industry is exporting more anime design, particularly the sci-fi genre; I don't think they will ever need an American hero to be 'localized' anymore. But it's always fun to watch some creative work of the past!