Tsurumaru Kuninaga a real sword, now rests in the imperial collection.
Tsurumaru always smiles, loves surprises (which often happened in his life), it may seem that he is not serious, but I was always interested in what he thinks about everything that happened to him. His master, Sadayas of the Adachi clan, dies at the age of 14 and the faithful sword goes to the grave for the child. But there is a surprise - a new child, Hojo Sadatoki, takes the sword in his hands, robbing the grave and Tsurumaru regains his master. In general, the fate of this sword is full of surprises, it really was snapped up all millennia ago.
The sword, one way or another, seeks to love its master, and all that Tsurumaru can do is to go with the flow and serve a new master, even if he himself killed the previous one.