u/Alternative_Fun9281

I’m curious if anyone can help me identify what is going on here. I bought a Tama Hime and I have it in mostly shade. I’m not over watering or under watering but it’s developing brown spots and the leaves are beginning to curl. My dad bought one too at the same time and his is doing the same thing. His gets more sun than mine. Is Tama Hime a more difficult cultivar? Is it possible mites or some sort of disease? Should I do a light dose of fertilizer? It started with small spots on a few leaves and has become more wide spread.

Any additional details you need to help figure this out, let me know.

Thanks for any advice!