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.

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.

Kou Yamori is an average middle school student who struggles with grasping the complex concept of love. Because he sees little sense in surrendering to the norm, he soon stops going to school. Plagued with insomnia due to his idleness, Kou begins roaming the lonesome streets at night. One night, Kou encounters a bizarre girl named Nazuna Nanakusa who believes that people stay awake during the night because they are dissatisfied with how they spent their day and cannot rest until they release their inhibitions. Nazuna offers to help Kou with his sleep issues and invites him over to her place, where she convinces him to share a futon with her. Feeling uncomfortable, Kou only pretends to doze off—which is when Nazuna suddenly bites his neck and reveals herself to be a vampire! While Kou thinks the bite will turn him into a vampire, the specifics of transforming are not that simple. In order to change, he must be bitten by someone he truly loves. Ready to let go of his dreary mortal life, Kou decides on a new goal: he will fall in love with Nazuna and become a vampire.

Nagi Umino and Erika Amano, a studious high school student and a social media star, had nothing that linked them together—until they found out they were swapped at birth. When the sudden news is revealed to both of their families, their parents quickly devise a proposition with neither Nagi's nor Erika's knowledge: in order to restore them both to their rightful families and ensure everyone's happiness, the two should get engaged. When informed of this, Nagi and Erika are quick to reject the absurd plan, refusing to go along with their parents' wishes. But, with neither party willing to back down, only time can tell where their relationship will go.