User blog comment:Machineman2005/Why is Battle Fever J among the Marvel Multiverse?/@comment-44176353-20191027070720

Short answer: Marvel wanted to sell "Battle Fever J" and other show which made in Japan with Toei, in USA. Marvel wanted their business bigger in Japan. Japan is big market, but "special" -in Japan, Marvel's share was very small. Then, Marvel's representative businessman, Gene Pelc, make an agreement Toei, which is one of big film makers, "to use each other IP freely for 3 years". So, Toei made Spider-man(famously giant robot Leopardon), Battle Fever J, Denjiman, Sun Vulcan, and two animation films, with Marvel's copy right (some old picture shows the copy right of "MCG"=Marvel Comics Group). Battle Fever J was an analogy of Avengers, in early plan, Miss America lead "Captains" of other countries. After Denjiman, Marvel and Toei agreed that they must success the shows, rather than taking Marvel characters. At last, Stan Lee loved "Sun Vulcan" so much, so he used the agreement which could use Toei's IP for Marvel. Marvel try to sold the TV shows (Spider-man, Battle Fever J, Denjiman, Sun Vulcan), but they failed. I don't know "when" the official Earth No.: in planning or when selling. However, it seem to natural when Marvel wanted to sell. And, one of Toei's producer said that Haim Saban was watched "Sun Vulcan" TV show, then he decided to buy Toei's Sentai show for over ten years before "Power Rangers".