Strike the Blood

A renewal of the non-aggression treaty between the Kingdom of Aldegyr and the Warlord's Empire is scheduled to be signed in the acceptably neutral Itogami City. King Lucas' misgivings about La Folia's relationship with the Fourth Progenitor result in him pressuring his daughter to quickly get engaged to someone. The Rihavein's host a large event that night and everyone is invited. Giant, flying, demon bugs crash the party and menace the attendees.

Lucas and Polifonia discuss the abduction with security. Meanwhile, with the two abductees bound and gagged nearby, erstwhile maid and now full-time terrorist Trine Harden discusses their plans while humiliating Kojo. The world is oblivous to the abduction which is kept from the public. On the day of the ceremony, at Trine's command, Kojo boards and takes over the Aldegyrian flagship, the Bifröst.

The Lion Agency and the Taishi Bureau have conducted a joint investigation on an unidentified marine accident occurring in the sea area around Itogami Island. On the other hand, Kojou wakes up after hearing a voice. The spectacle that jumped into his sight, whose memory was also dim, was a blanket and a cheek that seemed to have been wrapped and sleeping, cheeking, and Yukina's face appealing with tears. "Senpai ... I lost something important ...".

Itogami Island is a manmade island in the middle of the Pacific Ocean where summer never ends. A high school student at Saikai Academy, Akatsuki Kojou, is on his way home from studying with his classmates, Aiba Asagi and Yaze Motoki, when he notices a girl in the Saikai Academy middle school uniform following him.

Yukina moves into the room next to Kojou's. When Kojou sees that she only has a bare minimum of furniture and necessities, he takes her to a hardware store. Kojou's younger sister Nagisa also insists on hosting a welcome party for Yukina, adding up to a very lively day.

The morning after the battle against the Combat Deacon and his homunculus, the town is left in ruins. Yukina had been shocked to see how vastly Kojou's power exceeded that of the Familiar, but now she learns that Kojou can't even control his own Familiars. Kojou and Yukina pursue the escaped Eustach and Astarte to an abandoned laboratory, where another intense battle awaits them...

Blue Elysium, a new fantasy marine resort, is holding its trial opening and Motoki wants the gang there. Kojo and Asagi end up working a yakisoba booth while Yukina and Nagisa see the sights. Elsewhere on the grounds, Sayaka rescues Yume Eguchi, a younger girl abductee but after giving the girl a photo of Kojo and sending her ahead to the lifeguard centre, is herself taken prisoner by a mysterious sword shaman

Kiriha Kisaki, who works for the Taishikyoku, an agency similar to and in competition with the Lion Kings, offers to release Sayaka once her mission is complete. Until then Sayaka will be put to work. Kojo discovers that Yume is a succubus demon, and her ostensible sister Riru is actually her own alter ego, concocted to cope with past trauma. The others all rise under her mischievous control and make advances upon Kojo.

While Asagi investigates, she is interrupted by Lydianne Didier, who reveals that she is working for the Taishikyoku, managing the LYL program and will protect their systems against all comers. She challenges Asagi to hacking combat and begins her attack. Lilith's spirit awakens early and automatically, contrary to Kazuomi's schemes.

Strange occurrences at sea result in Itogami Island becoming isolated. Nagisa continues to suffer effects from her previous exertions. A terrorist group known as Tartarus Lapse begins operations on the island.

The terrorists launch an attack upon the warehouse district. Afterward, Kojo and Himeragi meet the terrorist leader, Senga Takehito, who tries to recruit them. He reveals his beliefs about the true nature of the island, its purpose of reviving Cain, and his plans to oppose this.

At Mogwai’s urging and with Motoki’s assistance, Asagi makes her way to the Keystone Gate in order to end the hacking attack upon the island’s network. Meanwhile, Kojo and Himeragi battle ineffectively against the demons unleashed by the terrorists.

Kojo is preparing to enter the Node and rescue Avrora, but the MAR, Led by the sister of the director Shahryar Ren, Radori Ren, intervenes. With the threat of a Tenbu ancient flying fortress, Radori claims she wants to prevent a war and demands that the Itogami Island be sold to the MAR.

Yukina is sent by the Lion King Organization to the bottom of the Keystone Gate to destroy the kagame stone, the keystone of the entire island, to sink Itogami Island and close the Node portal. While she hesitates to use the Sekkarou to complete her task, Kojo arrives to stop her, determined to fight to defend the island.

Radori Ren tries to show the strength of the Dantou Familiar to Kojo and the others by destroying Tokyo. Meanwhile La Foria who leads the fleet of Knights of the Second Coming attacks Shito (Carena City).