is a simple gambling game played in Japan using one covered die. The dealer shakes a six-sided die in a cup or rice bowl and then places it upside down, concealing the rolled value; after the players wager for their prediction of what the value will be, the dealer reveals the die by lifting the cup.
The dealer is known as the , while the bettors are the ; the dealer is the one who holds the cup, known as the or . The role of the dealer may either be fixed to one person or rotate amongst the players.
Players wager by placing money on one of six spaces on the game board. Winning wagers are paid out typically at four-to-one (e.g., a player who places a $10 bet on a winning space would be paid $40) while the dealer keeps the losing bets. The winning payout may vary between 2:1 and 5:1.
Consider a player who places a total bet of , with wagered on each space: one space will win, and the player will receive ÃÂ for that bet, but the other five spaces will lose, costing the player . The difference between the amount the player loses and the amount won is the house edge; with a multiplier of 4, that difference is , which is (%) of the initial bet. Formally, the house edge is computed using the relative probabilities of winning and losing along with the winning multiplier, :
The house edge varies from % (for a multiplier of 2) to % (for a multiplier of 5), with the most common multiplier of 4 resulting in a house edge of %.
There are multiple variations using up to five dice, although multiple-dice games generally have different rules, including Chà Â-han (2 dice) and Cee-lo (3 dice).
The game was noted to be so popular by the 18th century that an entire strip of gambling sheds one long, , was dedicated to it.
At least two stories use choboichi as a central element: and .