There are two endemic pests on the island: deer and leeches, both of which want to eat things you'd rather keep to yourself. When hiking, keep your trousers stuffed in your boots, and if you do spot leeches remember to use salt or fire to dislodge them, not brute force. Absolutely do not try to feed the deer or the monkeys.
buy, eat & drink
The shrine maintains a monopoly on food, drink and souvenirs on the island. Prices are not unreasonable, and many try the seafood here yes, whale is also available.