Gwisin
Gwisin (귀신) is the Korean term for ghosts and superhuman spirits, rooted in the Chinese characters for 'ghost' (gwi) and 'spirit' (sin); in everyday usage it means the restless dead. A person who dies violently, unjustly, unmarried, drowned, or without proper burial or ancestral rites can remain in the world of the living as a gwisin, bound by han (accumulated grievance). Documented from the Samguk Yusa through Joseon-era yadam collections, gwisin belief sits at the intersection of Korean shamanism, Confucian ancestor rites, and Buddhist afterlife ideas.