Lewis and Okamura confirm Solomon's story that Amshel is a chevalier. Saya agrees to go fishing with Gray, Kai, and the children. David and Joel drop in on a party being held by Amshel and Van Argiano to celebrate the American branch. While there, David talks with Julia, but is interrupted by Dr. Collins. Joel also talks with his "Uncle" Amshel, discussing the new business. Mao and Monique talk about their respective feelings for Kai, and his lack of feelings for them. To Van's shock, Amshel makes him the CEO of the Cinq Fléches' American operations due to Solomon's continuing absence. Saya is sleeping longer and becoming harder to wake up. The next day, the group says their good-byes to Gray, Monique and the children and heads to New York.

In New York, Saya rests in a hotel room and receives more blood transfusions while Hagi takes care of her. With her condition worsening, Saya grows more contemplative. She apologizes to Hagi for making him a chevalier, but Hagi assures her he has never regretted it. Solomon goes to where Diva and the others are, wearing a black suit instead of the white suits he used to prefer. Solomon asks Diva if she remembers the day they met. He tells her that he can not see Saya as his enemy and proclaims his love for her. Diva tells him to do what he likes and strips him of his role as her chevalier. Amshel refuses to let him leave alive, but Nathan stops their fighting and Solomon says he will live with Saya as Solomon Goldsmith.

A month after the last epiosde, the apartment Okamura and Mao in Los Angeles were using is blown up, so they join David and the others at their cheap apartment in Little Italy, New York. Saya is continuing to grow weaker and requiring more sleep. Mao makes her promise to return to Okinawa and go shopping with her after everything is over. Kai and Lewis meet with one of Lewis' old CIA contact, and learns that Goldsmith has deep connections to the US military and the Secretary of Defense. While meeting with a retired general, Joel learns Diva will be performing at an Air Force base in North Carolina. Mao overhears Hagi and Saya talking about Saya's time to go into her 30 year hibernation approaching. Though she's furious, Mao agrees to keep her secret and makes a promise with her that no matter what, Saya will return to Okinawa. Meanwhile, Van puts Dr. Collins in charge in the research division at Cinq Flèches, while Amshel has Julia replace Dr. Collins as Diva's primary care physician. Julia learns that Diva is pregnant and that Amshel is one of Diva's chevaliers.

Saya and her group have infiltrated the air force base. Following Julia, David learns Diva appears to be eight weeks pregnant and that the babies will be born soon. Once Julia and Collins are alone, he attempts to kill her, but David intervenes and is shot. At the same time, David manages to stab Collins in the arm with a scalpel, after which Collins runs away. Meanwhile, Amshel captures Kai and takes him to Diva, who wants to make him a chevalier. Saya is able to get Kai away, but when she goes after Diva, Amshel captures her, and Hagi is caught by Nathan. While they fight, several people attending the concert suddenly change into chiroptera and begin killing the other guests, only to be killed themselves by the Corpse Corps. Solomon appears and saves Saya from Amshel before flying off with her, after which Hagi frees himself from Nathan's grasp and leaves to rescue Saya.

Saya wakes up in Solomon's New York penthouse apartment, while Hagi searches for her. Solomon explains that he has left everything behind for Saya, including Diva. He pledges his eternal loves and asks Saya to be his bride. He pledges to protect her and fulfill her every wish. As they talk, Solomon realizes Saya's time of sleep is coming, and swears he would kill Diva if Saya ordered him to. Hagi appears to retrieve Saya, saying she is his reason for being. Solomon won't let her go, and they begin a battle. As they fight, Saya gets dizzy and falls from the building. To save her, Hagi unleashes his true form for the first time in the series. When they land, Saya gently rejects his feelings, and tells him killing Diva is her job. She and Hagi fly off, returning to the apartment. Meanwhile, Julia goes with David to the hospital. As he is rushed to the emergency room, he asks her to come back to them. Julia keeps vigil over him as he lies unconscious in the hospital, and kisses him. Back at the apartment, Mao kisses Kai and confesses her love, but also accepts that his only thoughts are for Saya.

Julia, Kai, Lewis, and Saya discuss Diva's pregnancy and David's slow recovery. Lulu comes to visit Saya again. Julia tells them what she learned about the Schiff experiment and the Corpse Corp and that they could suppress the Thorn in the Schiff with Diva's blood. Kai takes Moses a shipment of blood, as part of their agreement that the Schiff won't attack humans if the Red Shield supplies them with blood. When Lulu returns home, Karman forbids her from seeing Saya and the others because they are too different from the humans. Moses enter and Karman yells at him too. As they argue, Moses and Lulu discover that Karman has been inflicted with the Thorn. Karman runs out, unknowingly passing James. As the sun rises, Lulu asks Kai and Saya to help her find Karman. Karman goes to a hospital and attacks a nurse, but then sees a vision of Irene and the other Schiff who've died. Realizing they are still alive in his heart, he leaves the woman alone. That night, James goes to see Moses, revealing that much of his body is now that of the Schiff and that he was rescued before Saya's blood could completely destroy him. He offers to help the Schiff try to cure the Thorn, just as Kai had. Moses finds Karman on the roof with his hood down so he can die in the rising sun, but Moses stops him and promises to save him.

Unable to find Karman, Kai and the others return to the apartment. Moses arrives and after apologizing to Kai, tells him he must die. Saya blocks his scythe swing, but Moses manages to knock Kai out of the window. Hagi catches him before he hits the ground. Kai runs, trying to stay in the light so Moses can't attack him. When Moses corners him in an alley, Kai tries to convince Moses to stop and find out why he's doing this, but Moses won't answer. Backed against a fence, the sunlight stops Moses and Kai escapes. He runs to Central Park, but Moses finds him again and begins chasing him around the forest. Meanwhile, James goes to the Schiff's hideout and tells Karman that Moses is going to kill Kai to save him, even though it won't really work. James tells Karman it is for his revenge, because the existence of the Schiff has separated him from the one he loves the most. After seeing his new half-Schiff body, Diva declared that James wasn't her James anymore and hates him. In the park, Kai manages to shoot off Moses hood, but then runs over to cover him back off so the light wouldn't kill him. Spurning Kai's sympathy, Moses strikes at Kai with a spike he grows on his hand, but Karman appears and takes the blow meant for Kai instead. Karman calms Moses down and before they left, asked Kai to give Lulu their weapons. They go to a bridge where Karman tells Moses they won't be forgotten since Kai will remember them and pass on those memories. Together they stand and face the setting sun, their hoods removed. As they are enveloped in green flames, they agree that they are glad they met. In the apartment, Lulu cries over their weapons.

Mao, watching Saya and Hagi talk and hold hands, asks Kai if Saya is her competition for his love. She sends him out shopping, then asks Saya to catch him because she has some embarrassing things on her list, then keeps Hagi from following by saying she needs his help around the house. At the subway station, Saya starts to faint, almost falling in front of the train but Kai catches her. Later, Saya promises Kai that she will always protect him and asks him to take better care of himself. Kai has a key of their father's bar made for Saya, so they can run it together. David leaves the hospital and returns to work. Saya and Hagi remember her making him promise to kill her, with his own hands, when everything is over. As he, Lewis, Julia, Joel, and Okamura discuss the situation, they realize the American government has Cinq Flèches deliberately creating chiroptera in America, and abroad, to create enemies they can then rescue the people from using the Corpse Corp. Julia explains to them that Diva's singing, when heard in person or a live process, it increases the effectiveness of the D-base that causes people to turn to chiroptera from 3% to 100%. Meanwhile, Nathan visits Solomon and takes him to see Diva and the babies, which Amshel "cut out of her stomach." Nathan tells him that now that the babies are born, he has no reason to fight his family anymore. To prove his commitment to Saya, Solomon attempts to kill Diva, but Diva easily defeats him and leaves him badly wounded. As Diva takes the babies inside, Nathan wonders if even a chevalier can survive such wounds.

In order to keep Diva's public performance from being broadcast, David, Lewis, Kai, and Okamura go to Staten Island to blow up the satellite dishes. Though she is growing weaker and more tired, Saya is determined to fight so she doesn't wake up in a world full of chiroptera. Hagi asks Saya to reconsider their promise, but she makes him ask her to fight again. Amshel orders Nathan to kill Solomon, but Nathan releases him from the dungeon instead. James, in his full chiropteran form, goes to the apartment and attacks Saya. When Saya attacks him, though, her sword bounces off his skin. Hagi and Lulu try to help her in the fight, but the three are losing badly. As James moves to kill Saya with her own sword, Solomon arrives and, in his human form, blocks James' attack. Solomon then swears that he is Saya's chevalier by his own choice and states that it is "beyond blood". He is able to make James drop Saya's sword, but as it falls, it slices Solomon near his chest. James is suddenly inflicted with the Thorn, and Saya is able to strike the killing blow to his head. Solomon tells her to call his name if she ever needs him, then leaves. Though Hagi sees the cut from the sword, Saya does not appear to. Amshel finds Solomon in an alley trying to hold on, but he crystallizes in Amshel's arms from Saya's blood on her sword. Nathan and Amshel are now Diva's only surviving chevaliers.

Saya, Hagi, and the Red Shield goes to the Metropolitan Opera House to try to stop Diva's performance. Before the show starts, Nathan tells Amshel that the world exists to showcase Diva's beauty, as was predestined before she was born. When Amshel says Nathan talks like he was there, Nathan says he was and that before Diva was born, there was their "mommy" and her faithful chevalier. Kai confronts Hagi and demands to know what else they are hiding besides the coming hibernation time and begs him to take care of her. While they talk, Saya slips the key Kai gave her into his coat pocket and whispers goodbye. Saya and Hagi go to try to kill Diva before she can take the stage, but before she can charge Diva, Saya grows woozy again and can't attack. Hagi attacks Diva, but she easily dodges him. Hagi and Saya fight against Amshel. After he knocks Hagi out, Amshel tells Saya that if she had never set Diva free, Diva could have been his and his alone. He admits he has a constant obsession with Diva, which he views as the ultimate form of love for her. Diva begins singing, and people in the audience begin changing into chiroptera. Lewis is able to blow up the relay stations, but it doesn't work because they relay the signal through the military satellite feeds. Kai, David, Lewis, and Lulu go to the relay vans and destroy all of the equipment to finally bring down the world-wide broadcast. They get surrounded by chiroptera and David is injured. Hagi attacks Amshel so Saya can go after Diva as Nathan watches from the audience with the babies beside him.

Grant, the Secretary of Defense, escapes, and leaves Van behind to face the chiropterans alone. Saya tries to explain to Diva why she wants to kill her to protect the humans, but Diva reminds her that she was the only one who was ever treated as a human being. Diva returns to her regular form while she and Saya argue over the existence of chiropterans. Backstage, Amshel tries to upset Hagi by reminding him that his parents sold him to Amshel for a loaf of bread, but Hagi tells him he is grateful because it enabled him to meet Saya. Amshel and Hagi assume their true forms and begin fighting, going through the roof outside where Hagi is badly losing. Meanwhile, Lewis runs out of the transmitter trailer as a decoy to draw the chiropterans away with Lulu's help while Kai gets David to safety. Hagi gets the upper hand on Amshel and impales him on the top of a skyscraper, but loses a wing in the battle. As Amshel tries to pull himself off, lightning strikes the rod, appearing to kill him by electrocution. Diva asks Saya is she is going to kill her babies as well, since she believes chiropterans shouldn't exist. Both load their swords with blood and begin their battle. Nathan, holding the babies, and Hagi watch from the audience, having agreed that in the end it is the queens' fight. Saya and Diva each impale the other with their blood-soaked swords, but Saya heals while Diva begins crystallizing. Saya cries and tries to help her, but Diva begins shattering. Nathan brings the babies to Diva, and she tells them good-bye and imagines herself holding them before she dies. Nathan says all she wanted was a family, something Amshel never understood, and explains that when she became pregnant, Diva's blood lost its potency. Nathan asks Saya to kill him, as he no longer has a purpose with Diva dead, and Saya does. Hagi comes up behind her and wraps his arms around her as she cries. Kai comes in and Saya tells him that she must die after she kills the babies.

With the song stopped and Diva dead, the chiropterans begin howling and the Corpse Corps stops fighting. Inside the opera house, Saya explains to Kai that she fears that if she and the babies live, they would be used as weapons of war. Kai promises to make anyone who won't accept them understand and to always protect and love them all. Hagi tells Saya that he has loved her from the moment they met and that for once, he is going to disobey her. Taking her sword, he begs her to live on and kisses her forehead. Saya cries and says she wants to live before kissing him. David bursts in and tells him to hurry and leave because Option D has been activated. Kai and Saya carry the babies as the group leaves, but Amshel, who survived his fight with Hagi, attacks the group, ripping off Hagi's arm with his breath attack. Saya swears to protect the babies, but when she tries to attack Amshel, Hagi grabs the sword from her and pushes her away before stabbing Amshel himself. As Amshel begins crystallizing, he stabs Hagi through the chest with his hand and the roof collapses on them both. Saya screams his name and the military planes begin bombing the opera house. A month later, Saya and the others are back in Okinawa. The number of chiropteran attacks continues to decrease and Julia, who is now pregnant with David's baby, has found a way to prolong Lulu's life. Nathan, who survived Saya's attempt to kill him, is seen at a press conference in America about the criminal investigations surrounding Van and Cinque Fleches' close involvement with the U.S. military. Saya and Kai are hosting a party at the reopened restaurant, inviting their friends from the Red Shield and their schoolmates. Okamura and Mao plan to go to the Middle East together. During the party, Saya slips outside and looks back at the restaurant with tears in her eyes before she collapses. Kai catches her and agrees to wait to tell the others. He carries her back to the Miyagusuku family crypt where she woke up. She wh