There is no mountain taller than Mt. Fuji in Japan.
Literal
Mt. Fuji [than-より] tall mountain [topic-は] Japan [in-に] [contrast-は] not-exist.
Xより高い山はYにはない — 'there is no mountain taller than X in Y.' A standard superlative-by-negation pattern. Japan's tallest mountain serves as the natural benchmark.