Something a little different! The short series The Woman Called Fujiko Mine was produced in 2012 (that's before Part IV) as part of the 40th anniversary of the anime and serves as a dramatic departure from the series as a whole.
As an anniversary project, it's a prequel to Part I – set in the late 1960s, characters wear the same outfits from 1, and their first meetings and interactions are shown. The art style, with character designs by Takeshi Koike (who you may know from Redline – watch the movie Redline!!) recalls the manga with a scratchy, exaggerated look. And as a short series with an overarching narrative, it broke from the one-and-done episodic style of previous runs.
But of course the biggest departure is that the focus is squarely on Fujiko – Lupin himself is absent from several entries! Fujiko Mine looking at her as a character, as a thief, and uses her as a lens to analyze "stories about women" in anime. Series director Sayo Yamamoto (who went on to, among other things, Yuri!!! on ICE) was the first woman to direct a Lupin series.
To be clear: this is a very mature series. Sex, nudity, and violence are far more explicit than usual here, and the show digs deep into trauma and sexuality in ways that often make it a difficult watch. In addition to Fujiko, these themes are also explored through Oscar, a young man working under Zenigata.
With all that being said – if more mature dramas are your thing, I consider this series well worth your time! But: it's certainly not an example of what to expect from Lupin (well, with one exception) and not something for all audiences – there's nothing wrong with passing it over.
Fashionable Tinfoil Accessories: The Consulting Analyst (2014): A very well-written and thoughtful episode-by-episode review and analysis. Heavy spoilers as concluding events are discussed throughout each post! but highly recommended for understanding and appreciating the series.