Final answer:
The statement 'Of Japan's four main islands, Hokkaido is too often overlooked by tourists' expresses an opinion regarding the attention Hokkaido receives from tourists, which cannot be objectively measured.
Step-by-step explanation:
The sentence 'Of Japan's four main islands, Hokkaido is too often overlooked by tourists' states an opinion. It encompasses a subjective judgment regarding the frequency with which tourists visit Hokkaido relative to the other main islands of Japan - Honshu, Shikoku, and Kyushu. By saying it is 'too often overlooked,' the speaker is making a value judgment that cannot be measured or proved objectively. While it is a fact that Hokkaido is one of Japan's four main islands, whether or not it is 'overlooked by tourists' is subjective and varies from person to person.