If you grew up in the 80's or early 90's like I did, there was no escaping the tsunami of green mutagen that was the Teenage Mutant Ninja Turtle franchise. From their humble beginnings as independent comic book characters to a popular animated TV show, best selling toy-line, and several successful live action films, the Teenage Mutant Ninja Turtles (TMNT) completely dominated the eyes and minds of not only American children, but kids around the world.
However in Japan, our beloved "heroes in a half shell" only got minimal TV exposure, and in a somewhat confusing manner. In the early 1990's there were apparently a few different Japanese dubbed versions of TMNT floating around in Japan, some of which were broadcast on several different TV networks. Each network aired only a specific portion of the series and many episodes were never even aired at all. It's easy to see why TMNT didn't catch on nearly as well in Japan, especially during a time when Japanese kids were already hooked like rabid junkies on epic superhuman testosterone fueled shows like Dragonball Z (which American kids didn't get a taste of until the late 90's).
Then in 1996 the Japanese toy company Takara, which had created the original line of Transformers toys (Microchange), released a brand new line of Ninja Turtles action figures that would seemingly appeal more to Japanese kids. Using a mash-up of popular Japanese hero, robot, and anime inspired designs, Takara called these new versions, "Super Turtles"... successfully making our beloved green heroes look absolutely nothing like what they should look like (pre-Michael Bay). Nice job asshats.
To help sell this new line of bastardized TMNT toys, TV Tokyo produced an animated two part OVA mini-series called 'Mutant Turtles: Superman Legend'. What the hell? Did this new series really need to exist? I don't think so, most Japanese people I know who grew up around that era have never heard of the fucking thing... but it does exist, and the marketing team behind it tried really hard to turn the Turtles into "superhuman" badasses. They even hired the composer and singer of the popular Dragonball Z theme 'Cha-la-head-cha-la' to write and record an opening song for the show to help ensure it's success. Here is the result...
So as you can probably gather from the lengthy intro proceeding the god-awful theme song, the explanation for the turtles transforming into Saint Seiya-esque "Super Mutants" is due to some sort of magical fucking crystal... Once again, did this shit even need to exist?
But of course that wasn't the first time (or the last) that the Teenage Mutant Ninja Turtles franchise had made some really strange decisions and decided to produce some really weird and fucked up toys...