Rock Paper Scissor Poker (じゃんけんポーカー) is a game in the Kakegurui manga played in the tournament during the Election and supervised by the real Kurara Kurokura. The eight participants are Yumeko Jabami, Mary Saotome, Midari Ikishima, Yuriko Nishinotouin, Yumemi Yumemite, Erimi Mushibami, Miyo Inbami, and Ibara Obami.
The game is played with a deck of 63 cards - 21 each of rock, paper, and scissors. Each player receives five cards and is given one discard round. Players then put a card on the table - the "head card". After a betting round, there is the showdown. The rules are the same as a normal rock, paper, scissors game. In case of a tie, however, the game is switched to poker mode: whoever has more cards matching their head card wins. There are five rounds, but during each one players have to pay a mandatory participation fee that is doubled every turn. In turn one, the minimum bet is 10 votes, then in turn two 20 votes and so on. The player with the most votes at the end wins, regardless of how many rounds are won.
Round OneMatch 1: Yumeko Jabami (62 votes), played against Erimi Mushibami (23 votes). Yumeko discards 2 rocks, making Erimi play scissors to ensure a victory or tie. It was a bluff, however, and Yumeko beat Erimi with rock, forcing Erimi to go all in on the next round. After Yumeko discards 2 rocks again, Erimi thinks she is baiting her into playing paper. Erimi confidently plays 3 scissors to force a tie, hoping to beat Yumeko at poker with three-of-a-kind. But, with a hand of five scissors, Yumeko won (85 votes).
Match 2: Midari Ikishima (16 votes) played against Yuriko Nishinotouin (31 votes). Midari went all in with a five card combo, and won with the same hand as Yumeko, ending with 47 votes.
Match 3: Mary Saotome (124 votes) played against Yumemi Yumemite (144 votes). Yumemi did not care about winning, saying that she would rather give her votes to Yumeko. After folding twice because of Yumemi's unrealistic raises, Mary took a blind gamble and won by playing scissors against Yumemi's paper. Yumemi is angered by Mary's confidence, causing her to go all in and play 4 papers. However, it was useless as Mary was counting cards and was able to guess Yumemi's hand, countering her with another scissors, ending with 268 votes.
Match 4: Ibara Obami (39 votes) played against Miyo Inbami (61 votes) in the final match. Due to large gambles by Ibara, Miyo folds in the first two rounds, as she mistakenly believes Ibara would never lie, and thus must have gotten excellent hands. In the next round, she stated that she had already "sprinkled her poison" on him. Ibara looked shocked, and ended up losing the game, despite not understanding how he lost. He then discovers that Erimi and Miyo were cheating together, and their plan is later revealed in Mary's match against Miyo. Miyo reveals afterwards that she did not actually use any poison, and ended with 100 votes.
Match 1: Yumeko (85 votes) played against Midari (47 votes). In the first 2 rounds, Midari immediately exchanged all 5 of her cards after looking at them. She folds in the first round and beats Yumeko with 4 rocks in the next. In the third round, Midari again exchanges all 5 of her cards. Unamused, Yumeko goes all in, which makes Midari go all in as well. Midari again plays 4 rocks, but ended up losing to Yumeko, who played 5 rocks. Yumeko reveals that she saw through Midari's cheat, which was to keep cards from her discarded pile on her chair, and use them again to achieve a larger hand. Yumeko copied her cheat, but revealed that she did not have to, as she could have also beat her with paper. Yumeko won with 132 votes.
Match 2: Mary (268 votes) played against Miyo (100 votes). After losing the first three matches, Mary is sure that Miyo is cheating somehow. She stands up, and then notices bumps on the cards, realizing that Miyo had been poking holes throughout her matches to indicate the cards. In the fourth round, Mary uses a pen to poke a hole in her head card, making Miyo think it is scissors. Mary goes all in, and Miyo calls, but Mary wins the round with paper, revealing Miyo's cheat. In the fifth round, Miyo goes all in, but Mary explains that she had card counted again, just as she had done against Yumemi. Knowing she had no chance, Miyo takes a poisonous pill and tells Mary that if she does not forfeit, she will not take the antidote, thus dying at Mary's hands. Mary unwillingly forfeits, but then Miri comes in and tells Miyo it is pointless to wager her life when she would still have to beat Yumeko, Terano and Kirari to win the election. The referee counts Miri's interference as a rule violation, and Mary wins by default with 368 votes.
In the final match, Yumeko (132 votes) plays against Mary (368 votes). By successfully predicting each other's hands via the bumps created by Miyo and Erimi, Mary wins the first 2 rounds and Yumeko wins the third. Until this point, they were each betting the minimum participation fee. It is in the fourth round that Yumeko raises, betting 108 votes, the exact number needed to bring them each to 250 votes. Yumeko wins, resulting in a tie. At this point, Terano Totobami realizes Yumeko is striving for two victors, in order to force Terano to pay the students who were betting on the game double the winnings. If both Mary and Yumeko win, Terano will have no money left to buy votes after the tournament. While Terano is confident that mathematically, it should be impossible for them to tie, Chapter 74 ends with both Mary and Yumeko playing paper, resulting in a tie and confirming that some cheat was used.
Chapters 75-75.5 show that Jabami Yumeko and Mary Saotome both draw 250 votes from Terano's cover-up attempts.