Will-o'-wisp is a mysterious and ethereal character from the anime series 'Mahoutsukai no Yome' (The Ancient Magus' Bride). Known for its ghostly, fire-like appearance, Will-o'-wisp acts as a guide and protector within the magical realm. This character embodies the transient and enigmatic nature of spirits, often appearing at night to lead travelers safely or sometimes astray. Within the series, Will-o'-wisp serves as a subtle reminder of the thin veil between the human world and the mystical, blending elements of folklore with the rich narrative tapestry of the series.