Ichiro Tachibana is a student obsessed with his teacher, the Solar Witch Yuko Morino. When his arrogant classmate Lily attempts to turn him into her familiar using a magical charm, the spell backfires, transforming Ichiro into a tentacle monster. Though Yuko helps him return to human form, Ichiro is left with a mysterious horn and a potent musk that triggers an unexpected and intense sexual attraction in Lily, leading the two into a compromising encounter.
While Yuko helps Ichiro manage his volatile mana to reverse his monster curse, a second horn appears, signaling a change in his condition. Ichiro uses his new invisibility powers to get revenge on the arrogant Lily during a school meeting, but the day ends in chaos when Yuko reveals she is pregnant and a mysterious new threat arrives.
Kaya Blanche reveals that Yuko’s condition is actually a forbidden resurrection spell orchestrated by the evil magician Eisen Faust. After Ichiro manages to thwart the initial ritual, he and Kaya track Eisen to his castle, only to fall into a cruel trap. Using a potent love potion and psychological torture, Eisen manipulates Kaya and forces Ichiro into a carnal act to further his dark ambitions.
Eisen Faust attempts to resurrect his master by using Lily as a vessel for a dark ritual. Just as Lily's life is threatened by a forced heart transplant, Ichiro breaks through Eisen's magic to save her. Following the battle, Ichiro celebrates his victory with a passionate encounter involving Lily, Ms. Yuko, and Kaya, leading to a new chapter as Kaya joins his school as a transfer student.