The Nim Type Zero is a game in the Kakegurui manga and the second game of Council President Election. It pits Yumeko Jabami, Ryota Suzui, Miyo Inbami and Miri Youbami. Runa Yomozuki serves as the Dealer.
Game is played with a deck of 4 four different kind of cards numbered from 0 to 3, with 10 of each in the Deck. All players will be dealt 4 cards each. Players will each play a card forming a stack, the player that plays a card that brings the total sum to above 10 loses, making it a game of chance. To add an element of skill, players are allowed to play like in poker, placing their bets and bluffing to make opponents fold. The game is played in 3 rounds so a loser is guaranteed each round. The loser's votes are distributed equally among the remaining players.
For fairness' sake a different deck will be used every round. A number between 0-30 will be used to split the deck, riffle them up, and the final deck is made.
The Serum is worth 100 votes. A needle point holder filled with poison will be used. Once a player loses they will have to prick their finger in it, also no more folds are allowed.
All players bet their vote chips, which equal their right to vote and be eligible to be the Student Council President. In the event a player has an insufficient amount of votes, they can incur in a "debt of votes".
An serum for the poison is at bet by the Momobami.
The game beings and Yumeko starts, she bets 30 votes, exceeding what she has. Miri calls as well. Yumeko reasons that since they will be in debt anyway it is better to go at it big. Next is Ryota who begins to panic at how the risk increased so rapidly. However he decides to play anyway, Miyo follows afterwards.
With the stack of cards made, the first round begins. Yumeko looks strangely silent and distracted. She plays a 3, followed by Miri's 2. Ryota plays a 1, he reasons that playing a 1 or a 3 could be dangerous since it could lead to a sum of 9 and endanger Yumeko if she has no 0. Nonetheless he believes Miyo to have participated on a 30 vote game since she must have a hand of low value cards to allow her to play. Miyo plays a 3, this causes a total of 9, so whoever lacks a 0 first will lose. Yumeko, Miri and Ryota play a 0, Miyo is unable to continue so she loses.
Miyo reveals she has enough votes to pay, without falling in debt. Her hand was revealed to be a 2, 1, 1, and 3, which Ryota thinks that the hand in question is bad so he wonders why she would pay such a high vote count for it. Yumeko begins to feel sick and her condition worsens.
The game is interrupted, and Mary Saotome who was with Vice President Ririka Momobami playing a game for 100 votes at stake, is called by Ryota who is to bring "somebody with lots of chips". Saotome realizes the setup orchestrated by the Momobamis and rushes to the game stage.
Runa states something similar happened during the match against Yuriko Nishinotouin as she suddenly collapsed and was diagnosed to have been poisoned. Miyo rejects at the idea that they are responsible, but nonetheless reveals the Inbami and Youbami family specialize in drugs.
Ryota protests that they be penalized but Runa claims she can't as the no poisoning was committed in the game, so the observers have no say in external affairs as it would damage the "absolute neutrality". Mary realizes that this was all a ploy to guarantee somebody with chips to come and play instead of Yumeko, using her purely as a means to amass more of them. Saotome takes Yumeko's place.
Miyo places two new rules. The serum equals 100 votes and losers must prick their finger in a poisoned needle. As Miyo holds the serum the terms are non-negotiable to Ryota and Mary accept them. Miyo gloats to herself that all it takes is a little of violence to shake the game and its rules to have a favourable outcome, while in disbelief of their seemingly pure feelings of friendship.
The game reassumes, Runa requests Miyo for a number like in the first round. She calls 19 so the deck is split in 19-21, shuffled and the final Deck is then served. Ryota tries to wipe the sweat from Yumeko, who barely conscious, whispers to his ear to "listen to what Mary has to say" as it will bring in a lot of fun. Ryota realizes Yumeko caught into something but is unaware to what.
Miri bets 30 chips as before. Ryota is given his hand with a 2, 1, 1, 1 which he deems as a bad hand as he has no 0 and only small values. Mary requests to see his hand, but Runa stops him as it would be cheating. She states that mistakes aren't penalized and to be more subtle. Mary insists that he shows his hand to everyone. Ryota protests as they will counter him, but she reassures that they will win if he does. Ryota decides to trust in Yumeko and Mary, so he reveals his hand. Mary raises the bet to 100 chips. Miyo reasons that Mary wants to win and at the very least sacrifice Ryota to ensure her safety. She further thinks that gambling is ridiculous and only violence can change things. Everyone calls in for 100 votes.
Miyo remember her childhood with Miri, and reminisces about how their family split causing them to be competitors, but that using their signals developed through years of interaction helped them pass unnoticed. They communicate using these signals, Miri's hand is a 3, 0, 2, 3 and Miyo's hand is a 3, 2, 0, 0. They believe they can survive easily as they have 0s and high values. They aim to destroy Ryota so they plan how to do so, Miyo suggests a course of action.
The second round begins and Miri starts, she plays a 3. Ryota is next he plans to play a 1, but Mary tells him to play a 1, Ryota does but is interrupted by Miyo. She tells him not to follow Mary's orders as she is trying to save herself and doom him. She insists that if she disobeys Mary, she can provide in a syringe for Yumeko, trying to place a seed of doubt in Ryota. He rejects this idea as it goes against the game that Yumeko and them want, so he follows Mary's advice. Miyo is next and plays a 2, Miri inquires, and Miyo states that they cannot get Mary this round but they can force Ryota to lose. If Mary plays a 1 or a 3, they can guarantee Ryota loses, the only way to avoid it would be with a 2, but reasons that Mary will play a 3 to keep Miri in check.
Mary's turn is next. She asks to the Momobami about being "exploited" and who the weak were. Miyo responds that Mary and Ryota are the weak as they are being forced to make bets they didn't want, while the Momobami lose nothing at all, and that the weak are forever doomed to be exploited. Mary claims there is some truth to her claims but that in this Academy they are now, the Momobami are the weak and plays a 2. Miri, Ryota and Miyo play a 0, 1 and 0 respectively. Mary's turn next, she plays a 0, since Miri has no more 0 she loses.
Since Miri doesn't have the votes, she pays with 3 serums instead. Miri asks Miyo to get a serum for her later. Ryota tries to medicate Yumeko but Runa forbids against it as the game continues. She orders that nobody will use any serum until after the game. Miyo tells Miri to not worry as the poison will take time. Miri pricks her finger.
The third round is next, Runa prepares a new deck and has Mary call a number, she calls 15. The deck is halved and shuffled, the final deck is made. Like before, Ryota reveals his hand, he has a 2, 1, 1, 0. He casts a bet of 5 chips. Miyo raises to 300 trying to make up for their loss. Mary raises it to 10,000. Mura laughs as the school only has 3,000 students, but Mary insists that since they can go to debt it is ok and Mura allows it.
Miyo and Miri discuss Mary's intention, Miyo believes she wants them to fold so as to secure the serums. Miyo wants to pay back at Saotome for calling them weak so she takes the call. Mary calls her a fool. Everyone raises the bet to 10,000. Ryota plays a 2. Miyo is next, she plays a 3, she analyses Mary and how Miyo thought of her as a weakling for accepting their rules so willingly but changes her mind as she sees a behaviour on her only done by the strong. Mary plays a 2. Miri and Miyo realize they are in trouble, as Miri informs her that with the pile at 7, only a 2 could save her. Miyo then realizes something is amiss with the cards they were dealt, they both have a 0, 1, 3, 3 and believes Runa did something.
Mary explains what happened, Runa shuffled using a trick known as a "Gilbreath shuffle" a way to shuffle decks that ensures that with a deck of 4 different suits, each 4 cards will always feature all suits. Since the suits in this game are instead the values 0, 1, 2, 3 in simple terms it means that in every game there were a total of four of each number, redistributed randomly. This is why Mary had Ryota reveal his hand, as this allowed Mary to know by process of elimination, know what suits the Momobamis had. Miri inquires that even if this is true she could not tell who had what exactly. Mary mockingly tells them she was sure to win. She asks Ryota if she spots anything in their combined hands, and he notices that him and Mary have all the 2, knowing this Mary says the Momobami's have one less play available and thus much easier to predict and that no matter what, they were doomed to fail from the very beginning. Mary thanks Ryota for his trust and further mocks that they believed the students of the academy to be spoiled brats, but that interestingly enough they made a bet they in a losing game.
Miyo protests this as claiming the Dealer was rigged. Runa counters this by stating she used this setup since the first round and that nobody was given unfair advantage. She faults Miyo's overconfidence in her poison and her incompetence and noticing her surroundings. Mura prides herself in the fact that even if poison is thrown into mix, no matter the circumstances, the school will make it so everyone, including the dead have a chance to win, being the true essence of a gambler that cannot be swayed by mere violence.
It is Miri's turn next and the poison affects her. She plays a 1, Ryota, Miyo and Mary play a 1, 0 and 0 respectively. Miri's turn next, Miyo tells her to play a 3 and sacrifice herself so as to allow Miyo in the election as she is in better shape. Miri obeys but wonders why she looks so threatening. Miri plays a 3 and collapses. The Momobami sisters, lose.
As Miri faints and is unable to prick her finger, Miyo takes Miri's hand and pricks her finger. She then takes her sister away and vows to destroy Mary the next time.
Due to Miri incurring in a huge debt of 10,000 votes, any votes she gets will be transferred to the winners, all but ensuring that she is out of the competition.
Yumeko is stabilized and looks better. Ryota thanks Mary for her cooperation and reveals Yumeko suggested to bring Mary to replace her. Mary believes Yumeko had realized the shuffle trick and gambled on the possibility that Mary would realize too, seeing that Yumeko is a bona fide "gambling addict" as she would gamble even her life.
Mary looms over Yumeko's face and mutters her intentions to be the Council President.