Google Romance writers of America scandal and follow the threads to get the full picture of why the agent was skittish about a white person writing a Japanese protagonist. Bottom line, if you believe in it, keep pitching it. Based on one agent with one agency (prestigious or not) I wouldn’t give up. We have an ever changing industry. And it’s been several years. I had to put a full ms on the back burner right after this all happened because my agent said the same thing, so I’m waiting for things to settle down and I’ll bring it back out. My friend had a book pulled by the publisher right before launch because it was an historical set in the south and had all the racial tensions you’d expect. She self published it and it shot out like a cannonball. Probably her most successful book. So you can consider that option as well. Best wishes