Occult Research Club

Occult Research Club
The Occult Research Club is just a front for Rias's 'family' (Her servants) to use in order to get out of school activities in case of an emergency, such as having to hunt down a stray demon or destroy a fallen angel.

All members of the 'club' use it as an excuse to exit the lesson, however Issei is usually taken out of activities by Yuuto, as he is the only club member in his class, besides Asia.

It also serves as a cover for the demons, as the use of school recources to procure the abandoned dormitory as a base prevents scrutiny from other students and means that the demons don't need to do additional work for the money to rent another safehouse or buy their own food.