The black swindler who once deceived Hitagi and the cause of Nadeko's curse. Kaiki is a capable conman, able to deceive multiple people to get the results he wants, usually being money. On one occassion, he has used the alias 'Suzuki'. Though he appears to be a deceitful man, Kaiki has tried to help others occasionally.
Kaiki's catchphrase is, "The lesson to learn here is to________."
Back in his college days, he had a crush on Tooe Gaen, and watches over her daughter, Kanbaru, as a favour to Tooe.
He is the narrator of Koimonogatari.