Indian Poker

Indian Poker (インディアンポーカー) is a type of card which allows one to view the dreams of another. They have been created and spread around Academy City.

Etymology
Indian poker, or, is a poker game where the players see the cards of the other players except their own. Each player is dealt one card which is displayed to the other players, traditionally stuck to the forehead like an Indian feather, followed by betting as to whether they have the highest card based on the other player's cards and their bets.

Principles
A dream is recorded on the card by someone who attaches a machine to themselves when they sleep. Then the person who has the card may view the same dream that was recorded on. The instructions for making the machine used to create the card was released by someone online for free. The machine is created by combining various artificial esper power toys. The type of dream inputed into the card will affect its color, with orange being linked to joy and happiness. To use the card, one must put it on their forehead when the fall asleep. It is also said that the cards are good for learning by having someone of high proficiency in some subject create a card, for example learning another language or becoming skilled in a sport.

Dream Ranker
Those with the ability to create great dreams for others are known as a Dream Ranker (ドリームランカー). Those that can create useful cards are given ranks, with the highest being "S" or "A" rank, whose cards can sell for lots of money.

Dream Ranker Arc
Misaka Mikoto is a introduced to and given an Indian Poker card by the Ringlet curl girl as an attempt to apologize for causing her and Shokuhou Misaki to quarrel. She explains it as a popular card used to peek into the dreams of someone. After receiving the card, Saten Ruiko explains its purpose and how it was made to Mikoto. After using the card, Mikoto dreams of a world filled with Gekota which greatly pleases her. She frolics around with the Gekota until she is led by one of them to a castle and meets the queen who turns out to be Misaki. She is then forced to be the maid of Misaki for the remainder of the dream. The following day she meets up with the Ringlet curl girl again and is invited to tea. On arriving she finds Misaki also there, displeasing both of them. The two then overhear Aogami Pierce, going by the Dream Ranker name BLAU, distributing erotic dream cards to various other boys for free. After hearing about cards that involve them, Mikoto and Misaki team up to destroy the cards and erase them from the memories of the boys.