Yagen Valley

Yagen Onsen (薬研温泉) is a hot spring located in the former town of Ohata, which is now part of the city of Mutsu in northern Japan.

The onsen consists of multiple ryokan surrounded by old growth forests located along the Ohata River within Shimokita Hanto Quasi-National Park.

Oku-yagen Hot Spring is located 2 km upriver and an outdoor bath (露天風呂, rotenburo) called 'Kappa-no-yu' .

The onsen was named after a tool used in the making of traditional herbal medicine, which it resembled.

In 862, Jikaku Daishi, who discovered Osorezan, suffered a great injury after he got lost.