Small wooden tablets, usually five-sided and about the size of a hand, distributed at Shinto shrines and Buddhist temples all over Japan. Ema means 'horse-picture' and was perhaps in origin (the earliest known ema date from the eighth century) a substitute for a horse offered to the shrine as a messenger or servant of the kami. In the Muromachi and Tokugawa periods o-ema (large sized ema) developed as a professional art form, and were offered to temple-shrines and exhibited in emado (ema-halls) as thanks for some benefit received or for their artistic merit, a custom which continues. Pictorial conventions developed among professional manufacturers of small ema, so that a dog depicted easy birth (as in the hara-obi), a phallus represented fertility, a padlock over the character kokoro (heart) indicated a vow of abstinence and so forth. Ema today frequently carry on one side a picture of the current year-animal (see Juni-shi) such as a dragon, snake or monkey and a pattern or image related to the shrine from which they are obtained, including in some cases the riyaku for which the shrine is known. On the other side shrine visitors inscribe their name, address and personal o-negai (prayerful request) either for a specific problem to be resolved or more generally for benefits such as good health or success in examinations (gokaku), work or marriage. Ema may also embody a vow, a message to a spirit, an ancestor or dead relative including an aborted baby (mizuko), thanks or appreciation for a successful recovery or a statement of resolve. Unlike talismans and amulets (o-fuda, o-mamori) which embody the spirit of the kami and are taken away, ema are messages to the kami or bostatsu which are posted at the shrine, but along with o-fuda and o-mamori the old year's ema are normally burnt at New Year.
A Popular Dictionary of Shinto. Brian Bocking.