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.