Kashima Island is just 400 meters from Hojo, short enough to just swim across. The island itself is only 1.5 kilometers around, and has a few paths to provide a variety of hiking options.
There is a ferry which will take you across in just a few minutes which runs about once every 20 minutes. The fee is only 200 yen round-trip. There are some snack shops and a restaurant built over the sea.
Of course, there is a temple on the island near the ferry dock, but I arrived fairly late in the afternoon so it was closed. I'm not sure if/when the inside is actually opened.
You can still walk around the grounds and take a peek inside.
Being a small island, there is a bit of beach which has covered platforms good for parties and barbecues. Camping on the island is free, though I recall reading something that registration was required.
There is an area on the beach designated for swimming, and the path around the island follows the water. (More on this later.)
In addition to modern structures providing amenities for visitors on holiday, there are some historic sites with a bit of signage.
Look closely and you'll see that there is some wildlife here, and in the mountain itself you'll find even more.
This chain of rocks provides a nice foreground view to the rest of the inland sea and the mountains across the water.
Most visitors probably don't venture far into the island itself. The beach, shops, restaurant, pier, and a deer corral (?) can be found on the side of the island closest to Hojo.
My plans on Kashima were to walk around the island and then to the top. Unfortunately, erosion of the waterside trail has closed it to the public for safety reasons. That didn't stop some people, and with more time I might have been tempted to see what could be found around the bend. But I still could head up the mountain.
The hike up is quiet and pleasant. There are animals on the island; there are wild miniature deer that roam around but mostly stay hidden from tourists.
There's a rest house on the way up, but I was a bit worried as I made my way through the forest that I'd get eaten alive by mosquitoes if I stopped. Bug spray, people. It's important in nature in Japan.
I did stop for brief seconds to take a few pictures of interesting trees and the route up. There are a couple other paths leading up that might bring visitors to the backside of the island.
The top has a TV transmission tower and an observation platform. At least the mosquitoes stayed away from the platform so I could get some photos.
The chain of rocks is a religious site and the ropes are changed in a ceremony every year.
Ferries run from fairly early in the morning until late evening, but the schedule depends on the time of year. The shops on the island closed early, and I visited during vacation time. Hojo is a fairly large town and is served by express trains, and I understand that there's a supermarket within 10 minutes of the ferry pier, so it would be good to come to the island with everything you need (food, drinks, etc). Iyohojo Station is about a five minute walk from the pier.