New to the school's customs, transfer student Yumeko Jabami finds herself unexpectedly challenged to a game of rock-paper-scissors by a classmate named Mary – a contest with surprisingly significant consequences.

Having lost her initial conviction in Mary, Yumeko escalated the contest with a significantly larger wager.

Itsuki, a member of the student board, proposed a game of pairs to Yumeko. Whispers had long circulated that Itsuki was undefeated in this particular contest, and now she set a carefully crafted snare for her opponent.

Driven by a fierce need to reclaim her position within the school's social order, Mary challenges Yuriko, a member of the student board, to a duel. The stakes are impossibly high, a contest framed as a matter of life and death, while Yumeko…

Yumeko met Yuriko's gaze, a subtle smile playing on her lips, and addressed her with a knowing amusement that suggested an intimate awareness of the snare Yuriko had so carefully constructed.

Following a momentous event, Yumeko received an enigmatic file from the student council. Simultaneously, a card game for those burdened by debt began.

Yumeko and Mary joined forces for a game of Indian poker against Kiwatari, the school's resident bully. He was notorious for wielding fear and intimidation to control those around him.

Despite possessing the means to clear her debts, Yumeko deliberately chooses to remain indebted, a condition necessary to earn a formal contest with the student board president.

Yumeko accepts the challenge, agreeing to play a game of ESP cards against the chair of the Beautification Committee, a game structured like Russian roulette.

Suzui, visibly anxious, facilitated the lethal contest between Yumeko and Midari. Elsewhere, Manyuda, a member of the student council, requested Mary's presence for an unexpected proposition.