Yep, this is a movie that seemingly exists solely so that audiences can laugh at Wendy Van Dijk donning a wig and riffing on and most flagrant Japanese stereotypes possible as the titular Ushi Hirosaki. It's a part Van Dijk created for a series of stunts on Dutch television in which she posed as a TV Tokyo reporter to goon visiting celebrities - raising the obvious question of why pretending to be a Japanese person acting like an idiot is funnier than being a Dutch person acting like an idiot - but there's not even the pretense that the joke is on the celebrities in this feature outing. This is pure, "Hey, look! Japanese people are wacky!" as played out by someone very definitely not Japanese.
Could there be more to it? Could there be some Borat level social satire here? Maybe, but I don't see it. And, speaking as someone who has actually been to Kazakhstan post-Borat let's just say the joke isn't considered very funny there.