Watch High School DxD Hero: Taiikukan-ura no Holy Online

Three additional adventures for the Kimengumi and friends. In the first episode, the boys fail their exams right before summer vacation and have to take supplementary lessons. The second episode is a mandatory school trip to the beach during summer vacation for a swimming competition. In the third episode school is back in session, the karate club is in danger when a new opponent appears.

It happened suddenly: The dead began to rise and Japan was thrown into total chaos. As these monsters begin terrorizing a high school, Takashi Kimuro is forced to kill his best friend when he gets bitten and joins the ranks of the walking dead. Vowing to protect Rei Miyamoto, the girlfriend of the man he just executed, they narrowly escape their death trap of a school, only to be greeted with a society that has already fallen. Soon, Takashi and Rei band together with other students on a journey to find their family members and uncover what caused this overwhelming pandemic. Joining them is Saeko Busujima, the beautiful president of the Kendo Club; Kouta Hirano, an otaku with a fetish for firearms; Saya Takagi, the daughter of an influential politician; and Shizuka Marikawa, their hot school nurse. But will the combined strength of these individuals be enough to conquer this undead apocalypse? [Written by MAL Rewrite]

The impulsive Yakuza Jouji was ordered by his boss to teach at a misfit-filled school. He now has to settle the score with a fated rival while falling head over heels for a colleague in the process.

The mutinous Musashi has been defeated, and the girls from Yokosuka Girls' Marine High School are safely back home. However, the Harekaze sustained critical damage during its final encounter with the Musashi and may not be able to sail again. Moreover, rumors spread that the Harekaze-class will be dissolved due to it lacking a ship. Other classes' attempts to scout members from the Harekaze's crew only make the situation even more uncertain. The answer to this dire problem may be found in the sealed orders that the secretary of the Harekaze, Kouko Nosa, is to deliver to its crewmembers. But time is running short...