Current owner: Anahera Hoshiko
This sword's name is such because of the kappa-head on the pommel of the weapon and because of the fact that the blade is actually hollow on the inside. Inside of this hollow are numerous storage seals containing nothing but water which, when released, pours out of the holes along the blade. Aside from providing water for Suiton techniques, the wielder can release a torrent of water as they swing the blade to drastically increase it's weight and momentum. Hoshiko has also been seen using it to cut wood and food but never sharpening the blade, which is a mystery to others, even the other Swordsmen of the Mist.