kaiken
kaiken is a tantō or weapon family.
Also recorded as futokoro-gatana.
Overview
Lightweight dagger which was commonly used by the wives of samurai during the Edo period.
In detail
kaiken is a tantō or weapon family.
Sources
Each source is named with the standing the house places on it, so the evidence can be weighed rather than taken on trust.
reference work · Reputable secondary · Wikipedia
“Kaiken (dagger)”, English Wikipedia, consulted as further reading
Consult the sourcereference work · Reputable secondary · Wikidata
Wikidata, structured authority record Q2497844: kaiken
Consult the source