Hasuike Castle, Mountain fortress in Shikoku, Japan

Hasuike Castle is a flatland hill castle (hirayama-jiro) on a small hill in the western part of central Tosa, Kochi Prefecture. It was founded in 1170 by Hasuike Gonnokami Ietsuna, a local lord serving Taira no Shigemori, and is a designated historic site of Tosa city.

The fortress was built during Japan's Sengoku period, when regional lords constructed fortifications to defend their lands during warring times. It reflects the military needs of that era and was eventually abandoned.

The castle was built following traditional Japanese defensive design, with concentric stone rings that remain visible today. Visitors can observe how the innermost and outer areas were separated by different elevation levels and fortifications.

The castle site lies on a small hill in the western part of central Tosa, now laid out as Shiroyama Park. Paths run through the park, which is known for its cherry blossoms. The hill is low but the ground is uneven, so wear comfortable shoes.

The fortress location allowed inhabitants to monitor multiple mountain passes and observe movement across large distances. This made it a key position in the network of regional control during the conflicts of its time.