The Okuoi region is outback territory that urbanization will never touch—a pristine prefectural national park guarded by mountains up to 2,000 meters high in the northern part of Shizuoka. The Oi River, which flows into Suruga Bay, runs through here. Lake Ikawa and Lake Hatanagi draw visitors, especially during the peak autumn season, and there are several onsen areas tucked into the valleys.
Ikawa Dam, which dams the upper section of the Oi River, and Nagashima Dam offer parks and walking trails galore. The Sesso Valley and its virgin forests run for about 13 kilometers along the river as it winds its way downstream through precipitous cliffs.
You can reach the Okuoi region by train, including the main leg on the JR Tokaido Shinkansen or Tokaido Main Line.
The JR Tokaido Shinkansen takes an hour to get to JR Shizuoka Station from Tokyo. From there, it's another 30 minutes to Kanaya Station by the JR Tokaido Line, and 1 hour and 10 minutes from Kanaya to Senzu Station via the Oigawa Line. By comparison, getting from JR Shin-Osaka Station to JR Shizuoka Station takes two hours by Shinkansen. You can use your Japan Rail Pass for the JR legs.
Kakegawa was both a post station and castle town on the old Tokaido route
The Ikawa Line is Japan's only alternate biting tooth rail system
The Alps Sesso great suspension bridge is the start of a hiking course called “Love Romance Road”
The valleys here boast some great onsen bathing, including Sesso-kyo Onsen between the Ikawa Dam and Nagashima Dam and Sumata-kyo Onsen in the Sumata Valley. Sumata-kyo's waters are famed for their beautifying properties.
You can enjoy Okuoi's beauty riding the Ikawa Line, which is the only alternate biting tooth rail system in the country. The line takes you through the mountains and across the Sekinosawa Bridge.
The Oigawa Railway—the only steam locomotive operating every day in Japan—allows you to relax and enjoy the view as it puffs through tea fields and other natural scenic delights. This train connects JR Kanaya Station and Senzu, a ride that takes about 70 minutes.
Okuoi is a paradise for hiking.
The "Love Romance Road," despite its name, is more challenging than it sounds. While you start the hike at Sessokyo Onsen Station, the main hike begins at the Minami Alps Sesso Great Suspension Bridge, a great bridge 240 meters long and suspended 31 meters above the water's surface. It is the biggest of eight suspension bridges along this trail.
The trail mostly follows the Oi River going upstream, crossing eight bridges. You might want to stop at Wakagaeri-no-Yu, a spa where you can soak for a rejuvenation—it's name means fountain of youth. The trail ends in the village of Umeji, where you can catch a train (the last train departs at 4:30 p.m.) back to Senzu Station.
Kakegawa was both a post station on the old Tokaido route and a castle town surrounding Kakegawa Castle. The castle has been restored to how it looked during the Edo period (1603-1867), and you can take rickshaw rides around the castle area.
You can hike around Awagatake, a small mountain east of Kakegawa. In spring, the city's iris garden boasts more than a million irises in bloom.
The castle has more to offer in the form of the Ninomaru lord's mansion, which is designated an important cultural asset, and one of only four still standing.
The striking and atmospheric Ninomaru Museum of Art has exhibitions featuring the possessions of feudal lords as well as works from well-known Japanese painters such as Yokoyama Taikan.
If you want to move halfway back to civilization, Tsumagoi is a 170-hectare resort area that offers a golf course, tennis courts, music facilities, event halls, restaurants, hotels, and more. Enjoy various outdoor and indoor sports such as archery, horse-riding, motorsports, cycling, fishing, and swimming in an indoor pool and a water park.