When doing a run today on my JP copy, I discovered two differences between it and the international versions that would afffect speedruns. Although I've just reported this to the Discord, I figured it would be important to get it down in our forum too.

• When naming your dog at the start of the game, pressing + does not bring you to the confirm prompt, instead just changing your keyboard to Kana. You have to manually scroll there with a left and an up press.
• The Petasi's Goodbye cutscene at the very end of the game, previously thought to be unskippable, can be skipped in the Japanese version, saving time.

With this, the Japanese version appears to save an entire cutscene over the American version. As I only have the Wii version of the game, I can't test this on PS2, but Auaora has said she might be able to help so hopefully we'll have an answer on that front as well.

Edit: Auaora has confirmed that it works the same way on PS2. Edit (27/9/21): another edit just to get in this thread that JP also has faster load times than US, enough to save several minutes. We've known this for a while but. yknow