A malevolent spirit that can transform itself into any form it likes. It can also remain invisible, in which case its presence is known only through its audible footsteps as it passes by. The sairo is believed to be capable of taking one's vital organs or to cause various illnesses that lead to death. These spirits dwell in large trees, in thickets near springs, and in isolated places.
Places which are known to be inhabited by the sairo are typically avoided.
- Jocano, F. Landa; Edrozo, Arnora. (1982). The Ilocanos: an ethnography of family and community life in the Ilocos region. Quezon City: Institute of Asian Studies, University of the Philippines, p. 223.