One day when 17-year-old Sagara Kurumi accidently bumps into a guy on the streets, reins suddenly appear and binds them both! What is this?! Things get even more confusing when the boy, Kaito, clasps her hands and calls her his master! When Kaito transforms into a reindeer it just becomes too much for poor Kurumi who's out like a light. But it does indeed seem like Kurumi's a Santa and Kaito's her reindeer and that they've got an important job to do on Christmas Eve~The first three chapters in the first volume are about this cute "couple" and the last one is a oneshot called Amai Kamiato.