I received a protective charm from my childhood friend with the instruction "Keep this with you until you grow up because it wards off demons," but when I peeked inside what I thought was a sacred ofuda talisman, it turned out to be a marriage registration form.

Childhood friends Lily and Finn. At age 14, as Finn sets out on a journey, Lily gives him a protective charm. He tells her to keep it safe until she grows up, but... Is this... a marriage registration form?