This is good for some serious hiking or beach sitting. Or spend two days and do both. It is very easy to get to. Take the JR to Omi-Miako. There is one train a day that leaves from Sannomiya and goes directly there about 9.30 am. That’s the quickest way. If you miss that, change at Kyoto for the train to Omi-Miako. At Omi-Miako the beach is one way the mountains are the other. The beach is very long and you can pick your spot depending on the amount of company you want. For the mountains just walk through the rice fields (there is a road) to a very busy highway. At the highway turn left and you will come to a river (there may not be any water). At the river turn right and walk uphill.
This can be a long walk and there is a bus that runs about every hour. It is about an hour’s walk with only one turn; when you come to a house with some vending machines, turn right. This will bring you to a ski-lift. The ski-lift takes you to a rope way, which takes you to the end of the the rope way. There you will find all kinds of trails leading in many different directions. This is not easy walking but it is deep woods, cold streams, a few monkeys and places to camp. At the top of the rope way there is a limited restaurant to the right. There is no map at the top, but trails are well marked in kanji. It would be best to have some kind of map before you start walking. There are probably other ways down but the rope way, ski-lift, and bus is probably the simplest and most relaxing. You can walk for as long as you like on top.
photo by A giau