Koyomi Shizuka (閑 古詠 Shizuka Koyomi) is one of the Three Saints, the leaders of the Lion King Organization, who sent Yukina on a mission to be the observer of the fourth primogenitor, Kojou. She appears as a senior high-school student of Saikai Academy who always observes Kojou and Yukina.
Koyomi has long black hair tied into twin braids and blue eyes. She wears glasses and the Saikai Academy high-school uniform and carries a book.
Koyomi is a calm and composed girl, although in battle she emits an overwhelming aura of pressure on her opponents.
Right Arm of the Saint
Emissary of the Warlord
Banquet of the Observers
Her unique ability, which is also her nickname as one of the Three Saints, called Paper Noise, let's her attack anyone at any point in time, making her a formidable foe. She also has the ability to read the mind of her opponents to a certain degree such that, when coupled with her ability Paper Noise, make her one of the strongest individuals in the world.
- The name Koyomi means "ancient, old" (古) (ko) and "poem" (詠) (yomi).
- Koyomi's surname Shizuka means "quiet, leisure, spare time" (閑).
- Koyomi's real name is Koyomi Hiina (緋稲 古詠 read as ひいな こよみ) as Koyomi Shizuka is the title that she has as one of the Three Saints of the Lion King Organization.
- Koyomi has a boyfriend named Motoki Yaze who is one of Kojou Akatsuki's closest friends.