A unusual and scarce Japanese tanto, possibly a kama-tanto, with unusual concave-form blade with blunt tip and single hole piercing, blade length 23cm, the tang with stamped signature and single hole piercing, with black lacquer-finished scabbard (blade lacking grip, scabbard lacking kogatana and mounts). Provenance: the collection of the late Roald Knutsen (1933-2025). Note: Roald Knutsen noted this as a very odd item. It is possible that it was a martial arts training weapon with sickle form and blunted tip.