Yotsuya Yuusuke along with his classmates Shindou Iu and Hakozaki Kusue have been transported to a strange and unknown world inhabited by mythological creatures. As soon as they arrive, they meet somebody calling himself the Game Master who then grants them a time-limited quest. To aid them in this quest, he also bestows Shindou and Hakozaki with the roles of a Magician and a Warrior while Yotsuya is randomly granted the role of... a Farmer?! This is how a hectic life of adventuring began for three students who now have no choice, but to complete random quests for several phases in the fantasy world if they want to stay alive and protect the real world from the demons and monsters they encounter. (Source: MU)

Nasa Yuzaki is determined to leave his name in the history books. Ranking first in the national mock exam and aiming for a distinguished high school, he is certain that he has his whole life mapped out. However, fate is a fickle mistress. On his way home one snowy evening, Nasa's eyes fall upon a peerless beauty across the street. Bewitched, Nasa tries to approach her—only to get blindsided by an oncoming truck. Thankfully, his life is spared due to the girl's swift action. Bleeding by the side of an ambulance, he watches as the girl walks away under the moonlight—reminiscent of Princess Kaguya leaving for the moon. Refusing to let this chance meeting end, he forces his crippled body to chase after her and asks her out. Surprised by his foolhardiness and pure resolve, the girl accepts his confession under a single condition: they can only be together if he marries her! [Written by MAL Rewrite]

Two years before the start of the series, Roberto "Coach B" Sebastián, Sr.'s son, Roberto "Basti" Sebastián, Jr., was killed by a gunman from a large syndicate which brought down the Barangay 143's Powerhouse team and led to today's events. Bren Park, a player for a Korean basketball team, had lost recently his family in a tragic accident during a snowstorm in South Korea that led him to quit basketball. However, following a revelation that he was his mother's child to a Filipino man, Bren went to Manila to search for him. Along the way, he joined a local basketball team, the Puzakals of Barangay 143.

Tanjiro, Zenitsu, and Inosuke go on their first mission together and venture to Mount Natagumo. Too afraid to go up the "spooky mountain" with Tanjiro and Inosuke, Zenitsu stays behind. Tanjiro and Inosuke encounter a mountain laced with spider webs and controlled by Spider Demons. These Demons have already dispatched countless Demon Slayers, forcing Kagaya to send in the Hashira as reinforcements.