Sanekata is referring obliquely to the well-know tale of Urashima Tarō, who was given a jewelled comb-box by his wife, the daughter of the Dragon King, and told not to open it until he saw her again. Of course, he disobeys her and instantly turns into an old man.

The lady has said to Sanekata, ‘I can’t lock the door,’ implying that he may open it if he wishes. With his poem he says, ‘I’ll leave it closed all night, unless you are more definite.’