Alexandre Gervais

Ema (絵馬) are small wooden plaques on which Shinto worshippers write their prayers or wishes. The ema are then left hanging up at the shrine, where the kami (spirits or gods) receive them. They bear various pictures, often of animals or other Shinto imagery, and many have the word gan’i (願意), meaning ”wish”, written along the side. In ancient times people would donate horses to the shrines for good favor, over time this was trasferred to a wooden plaque with a picture of a horse, and later still to the various wooden plaques sold today for the same purpose.Wikipedia