Fantengoku High (Fan Heaven High in English) is the setting of Fantendo no Imouto, and a magical school created by the Halloween Spirit for all of his 366 children. Due to the Halloween magic it was built with, every day in Fantengoku High is Halloween (October 31st) relative to the rest of the world; this causes some temporal issues for travel into or out of the school, but all of the students and staff remain on campus in the dormitories and there are rarely any visitors.
A school-wide message board/forum was created by some of the students at the school, which is known as Fantendo (a clever pun on the school's name).
- Halloween Spirit: Principal
All of the teachers at the school are magical constructs created by the Halloween Spirit; they appear as somewhat incorporeal humans with carved pumpkins for their heads.