Apart from Lupin, I would say Takahata’s best-known work is Grave of the Fireflies. Roger Ebert lauded the movie, saying it
belong[s] on any list of the greatest war films ever made.
(Seriously, go see it and bring tissues). The film is firmly anti-war, and there’s a good reason for that. Isao Takahata was born in 1935, and in 1945, at the age of nine, his city of Okayama was bombed heavily by the US. Takahata survived, but the moment stuck with him forever. Takahata famously said,
You cannot keep the peace by picking up a weapon.
If you are interested in seeing any of Takahata’s movies, here are some links to each of them:
Nausicaä of the Valley of the Wind- (Physical)
Grave of the Fireflies– (Vudu) (Hulu) (Physical) (Ghibli Fest)
Only Yesterday– (Physical)
Pom Poko– (Physical) (Ghibli Fest)
My Neighbors the Yamadas– (Physical)
The Tale of Princess Kaguya– (Physical)
If you can, see as many as possible. He was a peaceful and beautiful creator.