Honen-ike Dam is located on the upper reaches of the Kinetagawa River in Kan-onji City. Completed in 1929, this dam is 145 meters long and 30 meters high, with five water spouts located at the front. These water spouts, called siphons, automatically drain the water in the reservoir when it gets full. The design of this dam, referred to as a multiple arch dam, is unique in that it appears to curve when viewed from above. The gentle curves of this giant dam are reminiscent of an old European castle.
The dam is important not only for its significant historical value as one of the earliest concrete reservoir dams constructed in Japan, but also as an example of early modern civil engineering at its best.
　Cutting-edge for its time, this dam provided work opportunities for the local people. These workers, who were originally farmers by trade, learned necessary construction skills through workshops and other instruction, and built the dam under the supervision of the national and prefectural government.
　Even today, this dam plays an essential role in providing irrigation water to farms downstream. The release of accumulated water all at once (called yurunuki) is a characteristic summer tradition of Kagawa Prefecture.