There's nothing like spending time by the water while you're on vacation. Enjoy an afternoon picnic at Watarase Reservoir and then hang around for an impressive sunset.
You'll be spoiled for sightseeing choice when visiting Oyama. Watarase Reservoir is an ideal place to kick off here, but there are many other interesting attractions to consider. Koga City Museum of History, Navel Park, and Tonegawa River Kasenjiki Green Space Park are near the body of water and will top off your day nicely.