Novelization for both the original anime series and the Ex series exist.
- Injuu Gakuen vol. 1 is basically a heavily modified retelling of episodes 1 and 2 of the anime series.
-- The illustrations are taken from the PC98 game. -- While the anime is known for its humourous tone, the novel is much more straight-laced, play the "ninja-fighting-with-sex" angle almost completely seriously, and is much more hardcore in term of content. -- The plot greatly diverges from the anime series and take some of its inspiration from the manga and the PC 98 game, with even more sex : for example, Miko's training now involves her grandma putting her hand inside her granddaughter to check on her progress; and the conflict against the Suzuka ninjas see Miko (as well as her sister and Nin-nin) being kidnapped and having to perform a non-stop succession of sexual battles against Bosatsu and Ranmaru : in quick succession, we have Miko being almost raped by an hypnotized Nin-nin, fighting a lesbian battle against Bosatsu, being sexually tortured with her sister by the two siblings, and made to participate in a ceremony-orgy to open the gate toward the Shikima dimension during which she has thirty men of the Suzuka clan ejaculating on her face, being played with by Bosatsu (before vanquishing her with her nyoninboh technique), and being raped, sodomized and ejaculated onto by Ranmaru; and by then she still has to go to the shikima realm to rescue her professor and her classmates... if you tought that the anime series didn't have enough sex, this novel is for you.
- Injuu Gakuen vol. 2 is a much more faithful adaptation of episodes 3-5 of the first anime series.
- Injuu Gakuen Ex vol. 1-2 adapt the events of the same anime series.