Tanuki. If you've never heard this word before, it may be due to lack of exposure to Japanese culture. Written using the katakana タヌキ, or the kanji 狸, the tanuki is an animal that exists on two different planes. In reality, tanuki are known as Japanese racoon dogs, native to eastern asia. In folklore, tanuki exist as shapechanging animals that enjoy mischief.
As real-life animals, tanuki are part of the Canidae family, related more to dogs and wolves than to racoons. Their strongest populations exist in east Asia and Japan, their native origin, and in central Russia, where they were introduced in order to improve the quality of local furs. The subspecies Nyctereutes procyonoides viverrinus is known more commonly as the Japanese racoon dog. It is this particular subspecies that lends itself to tanuki folklore.
In Japanese mythology, tanuki are considered naive pranksters. They are identified by several characteristics: large bellies, straw hats, sake bottles, and humourously large testicles (see above picture). According to Wikipedia, "Tanuki may be shown with their testicles flung over their backs like travellers' packs, or using them as drums." Tanuki have the innate ability to shapeshift, often assuming the forms of kettles, wandering monks, or even geisha. They also have a habit of cheating merchants by crafting fake money from leaves.
Tanuki are often seen in contemporary times in the form of statues. These statues can usually be found decorating shrines or shops. The Japanese symbol for the number eight, hachi ( ハ ) is written on their sake bottles, representing the eight traits of good luck that tanuki possess. These traits are: a hat to be ready to protect against trouble or bad weather; big eyes to perceive the environment and help make good decisions; a sake bottle that represents virtue; a big tail that provides steadiness and strength until success is achieved; over-sized testicles that symbolize financial luck; a promissory note that represents trust or confidence; a big belly that symbolises bold and calm decisiveness; and a friendly smile.
For more information regarding tanuki, I recommend you check out the animated film Pom Poko, created in 1994 by the animation studio Ghibli. This film deals with a group of tanuki trying to save their natural habitat from the ambitions of mankind, and makes gratuitous references to Japanese folklore in the process. It's a fun movie for parents and children alike, and has a simple learning curve.