Ryuji, I just went into the darkroom for a squiz, the film is flat.
I know when processing this film it feels thick and stiff when putting into the reels.
It doesn't seem to have a memory problem from what I can recall. I haven't used it since last October with some learner photographers!
As I dry by hanging in room temperature I don't know whether it would have an inward curl. As this film would more than likely be R/T processed, I think it would be designed to stay as flat as possible.
I forgot Estar is a Kodak name.
)
Mick.