Martha

The ghost of a high-school student who was an occult fanatic. 

Due to a ritual she attempted with two friends, they unknowingly angered a spirit which decided to curse them after death. Sometime later, the three of them passed away in certain circumstances. They all went to Somnis, where the curse manifested; their souls are cursed to follow a routine of going to school and back home afterwards, with said spirit as their teacher. Regardless, Martha still enjoys her presence in the world of spirits.