The Sixth Diary user. A frail girl with bad eye-sight, she is the leader of the Omekata cult where she's serves as the group priestess. The scroll she carries is actually her Future diary called the Clairvoyance Diary which allows her to read what her followers see. However, Tsubaki does not trust what her diary tells her because what her followers see may not be accurate and her fear of traitors from within.
Tsubaki is introduced after Yuki, Yuno and Keigo are invited to her cult's shrine to help deal with a Diary user who is disguising himself as one of her followers and planning to kill her in exchange she surrenders Minene to them after her cult captured her. Yuki agrees to help her due to her condition and Tsubaki's claim she has no interests in winning the game much to Yuno's jealousy. When the Twelfth diary user Yomotsu takes action to kill Tsubaki by hypnotizing her followers, Yuki and Yuno protects her and kills Yomotsu. However, Tsubaki betrays everyone, revealing she was using Minene as bait to lure them so she could trap and kill them and tells Yuki that she lied about not being interested in the game as she wants win and end the world as she hates it.