I have an expensive shirt with Mount Fuji on it which is considered holy in Japan. Is it haram to wear this shirt?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

The basic principle about clothes is that they are lawful and permissible until it becomes clear that they are prohibited.

The mere fact that the mountain is regarded as sacred by some people does not make it forbidden to wear the shirt that includes its image.

Allah Knows best.