  A new reactor-neutrino oscillation experiment, KASKA, is proposed to measure
the unknown neutrino-mixing angle $\theta_{13}$ using the world's most powerful
Kashiwazaki-Kariwa nuclear power station. It will measure a very small deficit
of reactor-neutrino flux using three identical detectors, two placed just close
to the sources and one at a distance of about 1.8km. Its conceptual design and
physics reach are discussed.
