Part I's popularity grew during reruns (perhaps because its low initial success made licensing cheap) and soon a second series was commissioned – New Lupin III, later subtitled Part II or referred to as "Red Jacket".
Clocking in at a hefty 155 episodes it is by far the longest-running series, and fittingly set several standards for the franchise. Lupin's red jacket (also Monkey Punch's preferred color for the character to wear) has become the default color for his garment. A new element was the soundtrack – jazz bandleader Yuji Ohno's new theme and background tracks would stick around ever since, and Ohno has continued composing new and rearranged soundtracks for the series.
This Part has a lighter tone and more exaggerated animation, inventive fun and high-energy heists of treasures from exotic and urban locales. Many episodes would get even wilder – featuring a mummy's curse, the Loch Ness Monster, vampires, and more out-there concepts that really show off the wide variety of what Lupin can do.
Stateside, Part II is probably best-known from the early-'00s dub that partially aired on Adult Swim (ultimately only about half of this series would be dubbed); it really feels in line with that irreverent adult-cartoon style of a lot of original Adult Swim series. Both English and Japanese dialog is witty, randy, and funny, establishing that rascally middle-of-the-road Lupin morality that most of the series sticks with.
All this adds up to a show that is great fodder for jumping in and around; in fact, you probably should – with so many episodes not all are gonna be home runs.