From Viz:
Sad at the thought of spending Christmas alone, Kurumi goes out for a walk. While she’s crossing the street, a boy bumps into her and a rein suddenly appears that binds them together. The overjoyed boy tells her she’s his master, and that she’s a Santa Claus. Kurumi dismisses him as a crazy person, but then he transforms into a reindeer?!

From Dragon Voice Project:
The first three chapters are about this cute "couple" and the last one is a oneshot called Amai Kamiato.

• Amai Kamiato -
Ren is a "tame" vampire and currently spends his lifetime with a detective as blood donor while in return he helps her investigate at night. Then suddenly, the most unimagineable thing happens: Ren's daughter Maia appears, but vampires can't have children!

Note: there's a side story of Penguin Kakumei in Vol.3, which hasn't been scanlated.