Tokushima, a middle-aged male teacher with a strong libido, finds himself targeted by Rima, a succubus from another world! Tokushima is bound and tormented by Rima, who tasks him with the retraining of failing succubi due to her overflowing libido. Iko and Ruku, the failing succubi introduced to him, are initially defiant, but after being subjected to a certain something using a mysterious tool…? First, the sassy brown-skinned succubus Iko's ecstatic retraining begins!