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Hokkaido is in the northern part of Japan.
Literal
Hokkaido [topic-は] Japan [of-の] north-region [in-に] exists.
北部 ('northern part') frames the location as a subregion of Japan rather than a bare directional 北 ('north') — a more precise, atlas-like phrasing. The polite あります adds formality suitable for informational or textbook writing. Hokkaido, Japan's second-largest and northernmost main island, is famous for snowy winters, expansive farmland, and Ainu cultural heritage.