According to Japanese folklore, tōfu kozō are small yōkai who closely resemble human children except for their large heads and clawed fingers and toes. They wear little boys’ kimonos and wide-brimmed hats — the typical outfit of a tōfu-selling young boy of the Edo period. They are usually depicted with two eyes, but in some illustrations they appear as having only one eye. They are usually found in urban areas in close proximity to people.

Tōfu kozō are timid and weak yōkai, and are not known to be aggressive towards humans. On rare occasions, a tōfu kozō may follow a human home on a rainy night, but for the most part they shy away from any confrontation.

Tōfu kozō are first and foremost servant yōkai. Even among other yōkai, they are often bullied and teased for their lack of strength. They get no respect from those above them; at most, they act as menial servants to more powerful yōkai.

Prior to the Edo period there are no known stories about tōfu kozō, and so their origin is a mystery. Some say that they are just one of many forms taken by an itachi, a shape-shifting weasel yōkai. Others say that they are the offspring of a mikoshi-nyūdō and a rokuro-kubi. Another possibility is that they are an invention of a creative artist looking to sell illustrated storybooks. Stories of tōfu kozō first appeared in the penny-novels and pulp fiction of Edo in the 1770’s, and became incredibly popular among the Edo upper class. These silly stories helped to spawn the explosion of yōkai-related fiction that appeared in the later half of the 18th century.

Tōfu kozō bears a very strong resemblance to another yōkai called hitotsume kozō — the chief difference being that hitotsume kozō has only one eye and a very large tongue, while tōfu kozō has two eyes and carries a plate of tofu. Both of these yōkai are somewhat weak, child-like creatures who act as messengers to more powerful monsters. In some literature the two yōkai are used interchangeably for each other, therefore it has been suggested that tōfu kozō may be closely related to, or may even have been copied from hitotsume kozō. However, there is not enough evidence either way to say where this yōkai comes from.