Born to the royal family, Pacifica Casull has earned the nickname Scrapped Princess after an apocalyptic prophecy foretells her destroying the world on her 16th birthday. Rescued from certain death by a kindly family, she takes shelter with her adoptive older brother and sister, Shannon and Raquel Casull. When news of her survival reaches the ears of the God Mauser's worshippers, they issue her death at all costs, forcing Pacifica to flee for her life. Plagued by threats from the church, the nobility and even the common people, the three siblings attempt to outrun the fate Pacifica is destined to bring, all the while questioning if one girl's life is worth the world's demise. The true nature of the Scrapped Princess, along with the harrowing revelations of the world itself, becomes more and more apparent as the princess' 16th birthday fast approaches.

Due to childhood circumstances, first-year high school student Saki Miyanaga hates anything related to mahjong. When she does play the game, she keeps a low profile to avoid standing out. One day, her friend Kyoutarou Suga drags her along to the school's mahjong club. There, she meets Nodoka Haramura, the champion of the previous year's national middle school mahjong championship, and Yuuki Kataoka, a fellow club member. As the club play a few rounds, Saki attempts to hide her talent. However, the club president, Hisa Takei, notices Saki's unusual playstyle. Realizing her potential, she puts Saki's real ability to the test—proving her to be more talented than expected. This revelation damages Nodoka's pride, and their relationship gets off to a rocky start. Saki ends up joining the club, and after clearing up the misunderstandings between her and Nodoka, friendship blooms between them. As Saki slowly warms up to mahjong once again, she and the rest of her club only have one goal—to win nationals!

With summer vacation coming to an end, the girls are having as much fun as they can with their remaining time. However, their daily shenanigans are cut short when Suguru Koshigaya wins the grand prize of a lottery—tickets to Okinawa! After hasty preparations, the Asahigaoka group embarks on a three-day trip for their final summer getaway. Upon arriving in Okinawa and checking into an inn, the group comes across Aoi Niizato—the young daughter of the inn's hostess. Despite being of similar age, her mature demeanor leaves Natsumi Koshigaya reflecting upon her own childish nature. With the sign of an unexpected friendship blooming on the horizon, the girls waste no time diving into their ambitious sightseeing plans and regional activities!

The fierce confrontation among the Kanto high schools reaches new heights with the awakening of dragons in the Kyousho and Seito Academy's leaders, Moutoku Sousou and Gentoku Ryuubi. However, the power balance between these two institutions and their main opponent, Nanyo Academy, is jeopardized when Shimei Ryomou seizes a mysterious dragon orb in China. It is said that the orb grants its strength to a dragon wielder, and Shimei hopes to save Nanyo Academy's leader Hakufu Sonsaku from the adverse effects of her unstable gift. Meanwhile, Moutoku's powers completely consume him, and he loses control over his own body to the Demon King's soul, whose unlimited ambitions endanger the stability of the region and the safety of his allies. In the face of growing tensions to claim the dragon orb, Hakufu and Gentoku will have to put aside their differences and work together to thwart Moutoku's demonic plans.