[5][6] In 1894, Queen Maria Christina commissioned Coloma to write a tale for King Alfonso XIII, who had just lost a tooth at the age of eight.

Coloma's tale follows Ratón Pérez who lived with his family in a box of cookies at the basement of Prast confectionery store in Madrid, but frequently ran away from home through the pipes of the city, and into the bedrooms of children who had lost their teeth.

The story details how he cunningly misleads any cats in the vicinity who may be lurking, and includes his interaction with King Buby (Queen Maria Christina's nickname for Alfonso XIII).

[8] Coloma promoted literature but was critical of novels in general, as he felt that they gave an overly idealized portrayal of human life and sentimentalized religion.

[3][4] In his later years Coloma only published biographies and writings of a historical nature, such as Jeromín, which focused on Don Juan de Austria.