Tsubaki Kasugano

Tsubaki Kasugano is the Sixth diary owner. Tsubaki is the High Priestess and Oracle of the Omekata Religion. Her followers know her as the "Sacred Eye" because of her supposed powers of clairvoyance, although this was a lie until she gained her Future Diary, the "Clairvoyance Diary". She is an 18 year old Japanese woman. Tsubaki is a slender, attractive girl with red eyes; her irises have a dull luster to represent her poor vision. She has long dark blue hair; some of it is pinned up with a red butterfly-shaped hairpiece or ribbon, while the rest hangs loose, partly covering the right side of her face and reaching her hips in the back. She wears a red-orange kimono tied at the waist by a thick white ribbon. Tsubaki's true colors are revealed along with her backstory; bitter, angry, and emotional, she despises the world, the Omekata religion, and her life. She deeply desires the power of God in order to destroy the world and recreate it in the way she sees fit. She's quite manipulative, having tricked Yuki, Yuno, Keigo, Minene, and Yomotsu into coming to the temple in order to eliminate all of them easily. She plays the false role of a damsel in distress in order to easily lure in Yuki, mocking his habit to quickly trust people against him.

Upon revealing her true self, Tsubaki attempts to quell her own pain by tormenting others, primarily Yuno. She kisses Yukiteru just to watch Yuno squirm and later suggests that several of her male followers gang-rape Yuno to lure out Yukiteru. This contributes to her ultimate demise, as she fails to consider how her actions could galvanize her victims or their allies; kissing Yukiteru prompts Yuno to attack her and nearly murder her on the spot. Tsubaki uses the Clairvoyance Diary, one of the few Future Diaries that doesn't take the form of an electronic device. It is a long paper scroll with a green scale design on the back; Tsubaki often carries it in the sleeves of her kimono until she needs it.

The Clairvoyance Diary records events through the eyes of the Omekata cultists, giving Tsubaki great control of her surroundings and any area her followers are in. Each follower's observations appears on the scroll with a label indicating their name and location; by reading all of the entries, Tsubaki can consider multiple elements of the imminent future across a wider area than most other diaries.

However, given its reliance on her followers, the Clairvoyance Diary can be disrupted via internal sabotage, which can confuse Tsubaki or limit what information she can glean from the scroll. Examples include when Yomotsu hypnotizes most of her followers, leading to all the diary's entries to reveal the same thing despite the followers being at different locations, or when Yukiteru throws a ball into the air, making all of Tsubaki's followers look at it for a split second. The Clairvoyance Diary also cannot directly predict the future aside from Tsubaki's own Dead End, forcing her to guess the immediate future based on her followers' observations.

Additionally, the Clairvoyance Diary is extremely vulnerable to damage compared to other Future Diaries. Being a long paper scroll that must be unrolled in order to read its entries, using it presents a large and extremely delicate target for Tsubaki's enemies - it is treated as "destroyed" even if it's only pierced by the point of a hand dart. As a result of this, Tsubaki often has to prioritize protecting her diary over defending herself in a fight, leaving her open to attack; against Yuno, this forced her to sacrifice one of her hands, leaving her even less capable of quickly handling her diary.

Tsubaki is a skilled manipulator, being able to lure three Survival Game participants and manipulate them into protecting her from the Twelfth with minimal suspicion of her true nature. Despite her partial blindness, she seems to be able to discern things rather well and act accordingly. Also, despite her crude past, her followers obey her every word, implying she is a respected leader despite her open desire to destroy the world. She is the leader of the mighty female lords! All females respect her!