Shungo Ninomiya is just an ordinary, run-of-the-mill high school student who lives at home with his older sister Ryoko—at least when she's not away doing her job as a mercenary. However, Shungo's life ceases to be normal the moment a cute girl named Mayu Tsukimura descends into the middle of his school's campus in a military-grade helicopter. It turns out Ryoko sent this girl, along with her older brother Mikihiro, to live at the Ninomiya household. But the newly-arrived siblings are a little special: Mayu is, in fact, a succubus and her brother, an incubus! And as if the circumstances are not problematic enough, Mayu is crippled with androphobia—the fear of men—and it's up to Shungo to help her overcome this at the behest of his sister. Ryoko plans to force Mayu to be closer to Shungo, and to do this, she’ll employ some questionable methods such as having them share the same bed and even take baths together. The situation further complicates when student council president Reika Houjou arrives as the new maid of the Ninomiya family, and she will stop at nothing to thwart Shungo and Mayu’s sexually-geared training. With the sudden arrival of all these oddities, Shungo's ordinary life is about to be thrown into utter turmoil.

It was announced at a Dengeki Game Festival stage event that the Strike the Blood light novel series will get a third OVA release. It will cover until the end of Seisen-hen. (Source: MAL news)

On a rainy afternoon, a male high school student awakens freezing on the streets with no memory of how he got there. His classmate and crush, Karen Inukai, finds him and takes him back to her home where, to his surprise, she starts to undress. She seems intent on bathing with him, though he has no idea why. When she holds him once more, he catches a glimpse of himself in the mirror—discovering that he has turned into a dog! Inukai adopts the puppy and names him Pochita. Now, he must adjust to life as a dog and figure out how to get out of this strange predicament. But while he mulls over an escape plan, Pochita sees a whole new side to Inukai that he never saw at school.

Douki-chan is a respectable office worker with one goal: to seduce her coworker Douki-kun. Unfortunately, this proves to be easier said than done, as her plans are constantly thwarted by Kouhai-chan and Senpai-san—her two love rivals who will stop at nothing to gain the affection of their beloved colleague first. Douki-chan will need all the luck she can get to surpass her competition and win Douki-kun's heart.