What language is the opening song to Devil Lady in? It doesn’t sound like Japanese. Also, what do the words mean?
Latin, I would guess. Sounds like it, and they seem to be going for a sort of The Omen-ish feel. No idea what it says, though ‘evil sounding sentence fragments’ would be my first guess.
Oddly enough, the opening theme doesn’t seem to have a name, and Toshiyuki Watanabe, the composer, seems to have a LOT of work to his name, so tracking it down from that end could be tough.
The show raises a lot of questions, aside from the theme song. Such as ‘How can one show have writing this good, and monster designs this bad?’ ‘How could they come up with an English title more awkward than Lady Devilman?’ And ‘How heavy can you make the lesbian overtones before you get to the ‘will you just kiss her and get on with it’ level?’ (Well, it DOES have Go Nagai’s name on it . . .)
Surprisingly good writing in fact, though admittedly Jun lacks Akira’s sense of fun . . .
‘In ultimate power, you’ll find absolution! Only God doesn’t sin when he kills!’
I should point out that the direct translation is “Devil Man Lady”
Transpostion error, I assure you. 
(Lady) Devil Man (Lady) at least makes sense in context. I understand why they changed it, but Lady Devil or Devil Woman would sound better.
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‘They stole this music from black people. But black people were just going to throw it away.’