Not a fan of the performance, but I'm part Japanese, and I dont find this offensive at all.
If she's not marginalizing or ridiculing Asian Culture, I don't really see what the problem is.
It's just fashion.
If anything - I would argue that it raises awareness and appreciation for a culture that a lot of her core audience is unfamiliar with.
I think people are also leftover upset from that time she said she wanted to skin Japanese people and wear them like Versace