The Kusafuka area is in the southwestern part of the town of Numakuma.
Literature on the town explains, "Kusafuka was originally a part of Shimosanna
but later became a separate village. The place was named Kusafuka, which
means overgrown with grass."
 On the southern tip of the Kusafuka area lies reclaimed land named "Isoshingai".
In the past, the area as far as Yorinomiya Shrine formed an inlet which
must have been overgrown with reeds.
 Roughly 50 hectares of land were reclaimed in the Kanbun era (1661-1673) by
the Fukuyama-han (feudal clan). A karahimon (a Chinese-style sluice gate) in
Kusafuka was built for the purpose of controlling water used for farming in the
newly reclaimed land, which was reclaimed by damming up the mouth of the
Sanna River.
 A stone wall was built in a corner on the east side of the dike, and a sluice
gate was constructed with stone and large wooden pillars. A pulley installed to
regulate the water flow played a great role in protecting agricultural land.
 In spite of two large scale repairs in the Edo period, the original structure is
retained. In 1982, it underwent disassembling and restoration. A pulley to
operate the sluice gate was restored on that occasion and a winch from the
Showa era has also been left as it was.