Another prequel – this six-episode streaming series features a teenaged Lupin finding the path that he will follow in his adult life. A bored rich kid frustrated equally by grandfather Arsène – who's handpicked him to follow in his thieving footsteps – and absentee father The Second – who insists his son stay out of the family business (both seniors making a very rare animated appearance!), young Lupin finds schemes large and small to get involved in, roping mysterious, dangerous delinquent Daisuke Jigen along the way!
Features some returning crew – head writer Ichiro Okochi also served that role on Part 5; director Daisuke Sako worked on part 5 and a few other Lupin projects.
This is set up as a prequel to Part I (as well as taking plenty of influence from the manga), featuring that series' unique soundtrack and set in 1960s Japan. Its streaming status lets it get away with a bit more juvenile delinquency than you might see on television – nothing too outré, just a little more gunslinging and peril than you might expect. At only six episodes long (standalone apart from the two-part finale), this is a brisk watch. It doesn't get too cute with overstuffing cameos – Jigen is the only member of the gang to appear, there's no "taking Fujiko to the junior prom", or "hall monitor Zenigata" sort of plots. It also doesn't do a Last Crusade-style explanation of every signature – indeed, apart from the newfound Lupin-Jigen partnership it kind of errs on the side of too little shifting over the course of things... it's more "see Lupin rise to the occasion" rather than "how [x] experience totally changed and actualized him!" But, after all, Zero does end with the duo still as schoolkids with a ways to go before the events of Part I.
Definitely worth checking out! I don't know if I'd recommend a non-canon prequel as the best starting point, but a fun watch and a great tonal introduction – the Lupintic humor, danger, action, comedy, and style is all very much in effect here.
"TMS Reveals Lupin Zero 6-Episode Net Anime Premiering in December", Anime News Network (2022)