This is a bizarre sex education manga set in a school, featuring a rowdy boy named Yakeppachi and a girl called Maria, who is Yakeppachi's ectoplasm. Yakeno Yahachi, a rowdy boy known as "Yakeppachi," conjures a pretty girl named Maria while in a trance, and her personality is identical to his. In fact, she is his "ectoplasm." "Ectoplasm" is a hazy, stringy, fog-like substance generated by a spirit medium during a seance, also referred to as an "astral body." Assuming the form of a doll given to her by Yakeppachi's father, the ectoplasm Maria begins attending school with Yakeppachi. The entire school is thrown into confusion, except for the homeroom teacher Akita, who is the only one to understand that this is a supernatural phenomenon. The plot thickens when a juvenile gang (the "Group of Tateyoko"), which has been watching Yakeppachi, discovers Maria's secret and starts following him, planning an attack. Another adversary of the pair is Yukisugi Midori, the girl leader of the "Group of Tateyoko," who is offended by Maria's popularity with boys and attempts to attack her with the intent to cause harm...