From what I understand, early Lupin was a MASSIVE scumbag. As a matter of fact, Monkey Punch, the man who created the original manga way back in the 60s, once said that if he directed The Castle of Cagliostro, that instead of Lupin rescuing Clarisse, he would've had Lupin rape her.

It's changed hands between a lot of various writers now who have generally hugely improved it. Castle of Cagliostro is a solid, charming-as-heck movie in my opinion. The Woman Called Fujiko Mine is a lot darker by contrast but it still yanks the reins hard away from making Lupin a charmless rapist. Why it got popular enough in the first place to start getting new incarnations, though, I have no way to explain.