Amano works in a hotel that caters to visitors from the other realm. When Tsukiyomi, the king of the other realm visits the hotel, Amano discovers the truth behind the disappearance of his childhood friend, Mitsuki.

Note: Polar Night is a reprint of Mangetsu no Ou, but with corrections, 36 additional pages, and the inclusion of doujinshi the mangaka wrote after the main story was first published. It also incorporates spin-offs from another of her works, Zhen: Tsukiyo ni Futari, Hajimete no Kanbyou-hen and a doujinshi titled Saikou.

This volume does not contain the unrelated oneshot, Jet Lag, which was included in the tankoubon for Mangetsu no Ou.