To start the training of the Cursed Gears, the Shinoa squad moves outside the wall to keep the damage to a minimum in case their demons get the best of them. Yu and Kimizuki must overcome their trauma to prove their psychological strength to their demons.

A student sneaks into the Forbidden Chamber, where the army keeps a demon for training. To show how dangerous a demon is, Shinoa takes Yuichiro and Yoichi there, but her plan fails when Yuichiro ignores Shinoa and starts to fight the demon.

Yu is caught in the middle of a political fight between Guren and Kureto Hiragi. However, Yu's determined to take care of his family - new or old. He assures Guren that he's on his side no matter what, and turns to him for help in saving Mika.

After his escape from the vampires, Yuichiro learns that humankind hasn't perished. Determined to get his revenge, he joins the Japanese Imperial Demon Army. Four years later, Yuichiro feels his training is enough, but his bad attitude gets him suspended.

Yu is caught in the middle of a political fight between Guren and Kureto Hiragi. However, Yu's determined to take care of his family - new or old. He assures Guren that he's on his side no matter what, and turns to him for help in saving Mika.

A deadly virus sweeps the earth, leaving behind only children and vampires. Yuichiro Hyakuya and the other orphans are captured by these vampires and are forced to provide them blood in order to survive. Fed up, they plan on an escape, but...

Trying to figure out what happened to Yu, Shinoa tracks down Guren and asks what he’s conspiring to do. However, Guren doesn't answer and keeps it a mystery. When Yu finally wakes up from a seven-day-coma, he explains he doesn't remember what happened.

Kureto's trump card was Mirai, Kimizuki's younger sister and another Seraph of the End test subject. In order to stop the Japanese Imperial Demon Army, Yu has no choice but to reach out to his inner "trumpet" to tap into the angel's powers.