Osenkorogashi, Coastal cliff formation in Katsuura and Kamogawa, Japan

Osenkorogashi is a coastal cliff overlooking the Pacific Ocean between Katsuura and Kamogawa in Chiba Prefecture. The rock walls rise steeply from the water and display varied layers, textures, and colors as you move along the viewpoints.

The coastal route along the cliff was only built in the Meiji era, around 1877-1886, because shipping was impractical on this wave-heavy Pacific shore; before that, roads along the coast were mere byways. In 1929 the railway (now the Sotobō Line) opened through the Kominato Tunnel, and a new National Route 128 later bypassed the cliff via the Osenkorogashi and Sakaigawa tunnels. In 1952 a family of three was murdered and thrown from the cliff in the Osenkorogashi incident.

The name comes from Osen, only daughter of the Kosen family, a local clan living near the cliff. According to the tale, villagers furious at her greedy father's raised tribute planned to kill him; Osen failed to dissuade him, wore his clothes in his place, and was thrown from the cliff in the night raid. Villagers found her body below at dawn.

The nearest station is Namegawa Island Station on the Sotobō Line. The old cliff-side path is reached by a road now closed with barricades and has no guardrails, so walking it carries a high risk of falling and is not recommended. The current National Route 128 bypasses the cliff through the Osenkorogashi and Sakaigawa tunnels.

The name comes from a legend about Osen, only daughter of the Kosen family living near the cliff. Villagers furious at her greedy father plotted to kill him; Osen failed to dissuade him, wore his clothes in his place, and was thrown from the cliff in the night raid. In the morning the villagers found they had killed Osen.