With the arrival of the U-17 World Cup, youth tennis teams from all around the world gather in Melbourne, Australia to determine which is the best. With nine-time champion Germany vying to defend their title once more, and powerhouse nations—Switzerland, France, and the United States—determined to make things interesting, the road to victory is perilous. Although Japan is sitting at the bottom of the rankings, the addition of the nation's strongest middle school players has reinvigorated their chances at winning. Captained by the ruthless Houou Byoudouin, Japan is ready to show the world what they are capable of. However, before the real competition starts, the teams will have a chance to prove their strength through exhibition matches. As luck would have it, Japan is slated to face off against defending champion Germany—a match they are likely to lose. To make matters worse, old allies have suddenly reappeared as sworn enemies. Before Team Japan crumbles under the pressure of the international stage, they must rise from the ashes and claim the title for themselves.

After surviving the brutal challenges of Idofront, Riko now possesses a White Whistle, allowing her to descend into the Abyss's sixth layer—The Capital of the Unreturned. Alongside Reg and Nanachi, Riko begins to explore the uncharted domain, where the ruins of the promised Golden City are located. As the trio starts to adapt to the harsh environment, they soon encounter dangerous creatures and treacherous landscapes. Their expedition leads them to a village inhabited by strange beings known as "hollows." Despite the creeping sense of unease that welcomes them, the three venture onward to uncover the mysteries of the settlement and long-lost legacies of the forgotten adventurers who once descended into the horrors of the unexplored Abyss.

E-Rantel, the capital city of the newly established Sorcerer Kingdom, suffers from a dire shortage of goods. Once a prosperous city known for its trade, it now faces a crisis due to its caution—or even fear—of its king, Ainz Ooal Gown. To make amends, Ainz sends Albedo to the city as a diplomatic envoy. Meanwhile, the cardinals of the Slane Theocracy discuss how to retaliate against Ainz after his attack crippled the Re-Estize Kingdom's army, plotting for the Baharuth Empire to take over the Sorcerer Kingdom. However, when Emperor Jircniv Rune Farlord El Nix arranges a meeting with the Theocracy's messengers at a colosseum, he is confronted by none other than Ainz himself. With their secret gathering now out in the open, the emperor and his guests learn that Ainz has challenged the Warrior King, the empire's greatest fighter, to a duel. With Ainz's motivations beyond his comprehension, Jircniv can do nothing but watch as humanity's future changes before his very eyes.

After Musashi rescues Michiru Saruwatari from a demon, his friend Kojirou Kanemaki discovers that his father was a member of the Uesugi clan. Determined to learn more about his own past, Kojirou—alongside his Kanemaki clansmen—decides to participate in Uesugi's punitive expedition against the demon lord of Awajima Island: Yamata no Orochi, an eight-headed dragon that threatens to engulf the entire region. However, upon joining Uesugi's military alliance, Musashi faces the harsh reality of fighting against powerful demons. Humiliated by his lack of power and inability to work in groups, he has to learn how to cooperate with his newfound allies. Meanwhile, the Obsidian Eight—a group pursuing the Obsidian Goddess that dwells within Musashi's body—resumes its hunt for Musashi, and plans to thwart the ongoing island operation. As the situation grows chaotic, Musashi and his friends must foil the machinations of the various factions conspiring to seize the Obsidian Goddess.