Yami said:
I think it's an evolution of the style that Takahata used on his previous film, My Neighbours the Yamadas. I seem to remember reading that Takahata decided to go down a minimalist route after talking with Canadian animator Frederic Back, who both he and Miyazaki were big fans of. But where Yamadas had more of a newspaper cartoon feel (think Peanuts), Kaguya reminds me more of the suni-e style that was used for Okami. I think it's breathtakingly beautiful.
I greatly appreciate this post, as I never made the connection to Frederic Back in regards to the animation but it makes sense when you look at it so thank you for that. The art-style in Kaguya is reminiscent of My Neighbours the Yamadas but seems to have a bit more of a 'flow' to it, if that makes sense? It's a bit more kinetic, and moves around like water, while retaining more detail in the backgrounds whereas Yamadas focused more on the characters, with often plain backgrounds, and like you said since Yamadas is based off of a comic strip, Nono-chan.
Kaguya does remind me a bit of the sumi-e (Ink wash painting) art-style used in the Okami video games, but less pronounced. A great art-style overall, and makes for beautiful looking games and movies. Can't wait for Studiocanal to announce the Kaguya Blu-ray