Isuzu is a young woman with light skin and light-brown shoulder-length hair. She is of average height and has large breasts. She wears a hairband with a flower on each end. Her clothes consists of a sweater, a black shirt underneath, a black full-length skirt and black shoes. She wears a necklace consisting of several round jewels. After the incident with her amasogi, Isuzu will at times tie her hair up.
Her younger form is shorter with a smaller chest. In this form she has similarly lengthed hair but tied at the side with flower decorations and parted down the middle.
Isuzu has arachnophobia.
Isuzu introduces Kiriha to the class upon her enrolment to Kamioka East Middle School and is happy to see the class's excitement. She tells Kiriha that dying her hair is against the school rules but Kiriha tells her it is her natural hair color. She assigns Kiriha to sit next to Kazuya Kagami where Kiriha is immediately bombarded with questions from her classmates upon sitting down. Upon hearing that Kiriha lives intimately with Kazuya, Shirou Shiramine takes over the class to hold a trial against Kazuya. Isuzu tries to stop them but is ignored. Isuzu appears flustered when Kiriha defends Kazuya, stating all the accusations of him sleeping and bathing together is what she wanted.
As more students fall victim to Isuzu's amasogi, Kazuya and his Personal Advice Club eventually deduce Isuzu to be the culprit and confront her. Mimane tells Isuzu to retreat into the dream world, leaving her unconscious in the real world. The club bring Isuzu's body to her home where they prepare to enter her dream. Isuzu speaks to Mimane within her dream world, expressing desire to stop what they are doing. Mimane finds that boring and manifests Isuzu's Shadow to replace her and take over the dream world. Isuzu somehow escapes and hides amongst the students as a younger version of herself.
After Kazuya and his allies enter her dream, Isuzu meets up with Chisato, Osamu and Shirou while Kazuya and Kiriha fight their shadows. She asks they help her kill the imposter but they ignore her believing her to be suspicious. Isuzu explains the imposter to be a shadow and the amasogi to be hidden within her body. Chisato asks about the location of the original Isuzu but Isuzu is hesitant to answer. Osamu catches on and decides they should trust her. Just as they finally agree to cooperate they are interrupted by Shadow Isuzu. Shadow Isuzu monologues about her desire to improve her lack of confidence caused by her students and peers' treatment of her, using the power of the amasogi and shadows. She summons shadow versions of the three students and tells them to accept their shadow selves. When they refuse, the shadows attack while Isuzu hides around the corner. Before Kazuya and his allies can be fully consumed by their shadows, Isuzu reveals herself, causing them to temporarily disperse. Shadow Isuzu summons more shadow students to attack but Isuzu uses a pair of chalkboard erasers to create a cloud of chalk, enabling their escape. Isuzu thanks the students for teaching her the courage to fight back and do the right thing before splitting up.
Isuzu confronts her shadow self one-on-one, using her previous trick to create another dust cloud and ambush her shadow using her more agile younger form. By writing words onto paper, Isuzu is able to manifest supernatural abilities to fight against her shadow self. After damaging her shadow a bit, Shaodw Isuzu uses her real students as a shield of hostages and commands them to pin Isuzu down. Her shadow tears up the paper that Isuzu was using to empower herself and prepares to swallow her. Isuzu is saved by Chisato, Shirou and Osamu who manifest their own amasogi to defeat their shadows, restrain the students and capture Shadow Isuzu. Shadow Isuzu breaks free by transforming into a giant spider causing Isuzu to faint. Kazuya buys enough time for Osamu and Chisato to wake Isuzu up, weakening the shadow enough to expose the amasogi within. Isuzu delivers the final blow to the shadow and destroys her amasogi. After the battle, Kiriha teases Kazuya after from having his clothes torn off during battle, to which Isuzu tells them not to have impure relationships. Bakura contacts them, telling them to go to sleep in order to awaken from the dream. Before awakening from the dream, Isuzu laments having to give up her youthful dream form and returning to reality
Within the real world, Kazuya and Kiriha are the last to awake. When they explain why it took so long, Isuzu expresses concern as a teacher. After the incident, Isuzu learned to be more assertive with her student in the real world and has stopped repressing her shadow self completely.
Isuzu explains to Kazuya and his Personal Advice Club that her amasogi was given to her by someone but she cannot recall who. Mana, Nanako Nanakai and Shirou attest to the same thing happening to them as well and they come to the conclusion someone is purposely causing the incidents.
Dream Pillow (夢枕, Yumemakura): A dream pillow amasogi given to Isuzu by Mimane Miyou. Isuzu used the pillow to grant her desire of actualizing her ideal self. By dragging students into her dream, Isuzu was able to act confidently around them unlike in reality. Once Isuzu expressed doubts about using the pillow, Mimane had Isuzu's Shadow take over her dream world. Though not in control of the dream anymore, Isuzu still possessed abilities within the dream world.
- Dream World Submersion: The pillow is able to trap near Isuzu with her dream world. When trapped, the target will remain asleep in reality and unable to awaken unless permitted to. Isuzu and her shadow have some degree of control over the captured victims, as shadow Isuzu is able to command them. Damage inflicted upon them in the dream is reflected in reality as well. Attempts interrupt the dream by destroying the pillow or murdering the host will result in all in the dream to remain trapped in a permanent slumber. The only way to be released from the dream is for the host to do so themselves or destroy the dream version of the pillow.
Dream World Abilities
Within her dream, Isuzu had access to numerous supernatural abilities even after her shadow took control over the dream.
- Chalkboard Erasers: Isuzu can clap a pair of chalkboard erasers together to create an unnaturally large cloud of chalk dust. This can be used to hinder her enemy's visibility, allowing her to escape or launch surprise attacks.
- Teenage Form: Isuzu is able to take the form of her younger self from ten years ago. By doing so, she is able to blend in with the students and goes unrecognized by her shadow self. While within the dream world, this was Isuzu's preferred form for combat as it was much more athletic.
- Yojijukugo Idioms: By writing yojijukugo idioms on a piece of paper and placing it within her mouth, it grants her abilities reflecting the written idiom. This ability is a reflection of Isuzu's self as a Japanese language teacher.
- Split Down the Center (
一刀両断, Ittō Ryōdan): Enhances the power of Isuzu's pointer swings, allowing her to perform strikes strong enough to cut off parts of her shadow's arm.
- Raging Inferno Surges Forth (沽火激発, Kogagekihatsu): Allows Isuzu to breath a powerful blast of fire at her target. Since the attack comes from Isuzu's mouth, using it destroy the papers.
- Burst of Strange Strength (
怪力乱神, Kairiki - ran shin): Enhances Isuzu's physical capabilities. Isuzu is captured before she can demonstrate the full potential of the ability's power.
- Reckless Assault (
猪突猛進, Chototsu Mōshin): Allows Isuzu to deliver a powerful one hit punch, strong enough to destroy her shadow's giant monstrous form and the amasogi within.
- Split Down the Center (
|Faculty||Isuzu Iriha • Meotoike • Nieda • Kukuri Shirayama|
|First Year Students||Nanako Nanakai|
|Second Year Students||Konoka Kobayashi • Mana Manaka|
|Third Year Students||Tadataka Tadata • Yuuichi Nishina • Yuu Osakabe • Sakumi Muratsuki|
|Clubs||Personal Advice Club|