I could hardly do Lupin III Month in the music topic:
https://trueleft.createaforum.com/counterculture-era/recommended-music-to-listen-to/msg23301/#msg23301without over here paying tribute to the mythos itself!
To me, Lupin III belongs strictly in the Counterculture era. Forcing the franchise to continue into the 21st century, and moreover not setting the new material back in the Counterculture era*, but instead actually mostly setting the new material in the ongoing present-day (which requires suspending the characters' aging), has led to its inevitable degradation in quality and meaning. For this reason, I myself ignore the TV series after Part 3. With the TV specials, movies and OVAs it is even more complicated due to overlapping retconning issues (e.g. First Contact), but basically I take less seriously anything beyond the early/mid-2000s at the latest.
(* The exception is Lupin Zero, which is a separate discussion, with even worse retconning issues. )
Other than the above reservations, there are further retconning issues with some Part 1 episodes but not others. So, in my mind, the canonical Lupin III mythos consists of only those Part 1 episodes which are strict causal prerequisites for subsequent stories, followed by Castle of Cagliostro as well as the complete Part 2 and Part 3, and then subsequent movies, TV specials and OVAs, with Part 2 prevailing over anything else in the event of contradiction. I should add that I would not have minded at all if the mythos had wrapped up after Farewell to Nostradamus** (trailer above), which was by far the most intuitive timing (voice actor death) for conclusion. The Lupin gang were inherently mysterious, almost aeonic characters who were meant to one day just vanish into thin air and never be seen again. Had this happened in the 90s, it would have been perfect. Now after decades of delay, they have become so overexposed that it is too late for a final disappearance to work well even if it did happen, but even worse that it continues to not happen.....
(** Note that although produced in 1995, the story occurs in 1999, thus still allowing inclusion of the late 1990s TV Specials, most importantly In Memory of the Walther P-38 which I definitely consider to be essential to the mythos.)_
Part 2 full episodes here:
Lupin III chronicles the adventures of Arsene Lupin III, the world's greatest thief, and his partners in crime: master marksman Daisuke Jigen, beautiful and scheming Fujiko Mine and stoic samu...