A marriage certificate between two characters. It originated as a meme template on Pixiv, likely as one of their many exercises in creativity.
All tagged entries involve the use of a template:
Pictures of the groom (left) and bride (right)
Names of the groom (left) and bride (right), including both kanji reading and pronunciations where possible
Date of Birth of groom (left) and bride (right)
A brief description of how the couple first met
Occupation of groom (left) and bride (right)
Miscellaneous other comments from the couple and/or any witnesses (friends, family, enemies, etc.)
Signature and hanko stamp of husband (left) and wife (right). Also acceptable are fingerprints, personal logos, bloodstains, etc. A simple signature is fine if nothing else will do.