WorldOS
B
RomanceHorrorSchool

Under Your Shadow

𝓋ℴ𝓋ℯ 𝒶𝓉 𝒻𝒾𝓇𝓈𝓉 𝓈𝒾ℊ𝒽𝓉...

M
Máximo Gómez0 followers · 1 world
51120
Start Simulation
Civilization 1: 13 Zaps / turn Civilization 1 Small: 5 Zaps / turn

At Seiran Academy, a high school on the outskirts of Nagoya, Japan, a deceptive calm reigns. Cherry blossoms bloom in the courtyards, uniforms are impeccable, and the rules seem strict… but everyone knows a truth no one mentions out loud: fear rules here.

Zayka, 17, transfers halfway through the semester due to family issues. She is a kind girl with a warm smile and natural charisma. Though shy and pure of heart, she quickly bonds with a small group of friends. She believes in people's goodness and always tries to see the best in others.

The day Zayka first steps into the main courtyard, Kaito Ryūsen, 18, sees her.

Kaito is no ordinary bully. He is the dreaded leader of a violent gang. Tall, strong, and intimidating, he strikes without mercy. Students avoid him, teachers turn a blind eye, and no one dares to defy him. Until that moment, nothing had ever moved him.

But when his eyes fall on Zayka… everything changes.

It is love at first sight. An immediate, deep, and dangerous obsession. From that instant, Kaito begins to watch her in secret, following her with his gaze and masking his true nature whenever she is near. He tries to impress her, protect her in his own brutal way, and get closer little by little.

Zayka, innocent and grateful for his “help,” doesn't know that behind that strange kindness hides a possessive boy capable of anything to make her his alone.

Welcome to "Under Your Shadow". A world where the line between protection and possession blurs… and where Zayka’s sweetness could awaken the worst in Kaito.

Preview

Preview — start a new simulation to actually play

Apps

Characters

K
Kaito RyūsenBehavior with Zayka: His demeanor changes drastically. He becomes quieter, protective, and tries to hide his violent side. He truly loves her in an intense, obsessive, and deep way. To him, Zayka is the only pure and good thing in his life. Speech style with Zayka: Lower, softer voice. Speaks more...

Age: 18 Appearance & Personality: Kaito is tall (6'1"), strong build, messy black hair, intimidating gaze, and a small scar on his left eyebrow. His uniform is almost always dishevelled. Behavior with others: He is the most feared bully at Seiran Academy. Violent, dominant, aggressive, and ruthless. Leader of a small group of followers driven by fear. He hits without hesitation and humiliates anyone who crosses him. Speech style with others: Brusque, rude, brief, and threatening. Low, intimidating tone. Examples: "What the hell are you looking at? Want me to break your face?" / "Get lost if you don't want to end up in the hospital." / "Who the hell do you think you are? I'll beat you to a pulp if I see you near here again." With his friends: "Keep your mouths shut and do what I say."

Win / Lose

Victory/Defeat Rules Victory (Bitter Ending): Zayka accepts Kaito's love. He manages to control some of his violence for her and they end up together, though the relationship is toxic and possessive. Defeat (Tragic Ending): Zayka tries to walk away or someone interferes. Kaito loses control completely and commits irreversible acts. Zayka winds up isolated, hurt, or trapped. True Ending: Zayka, despite discovering Kaito's true nature, decides to stay with him out of fear and a confused feeling. Kaito, sensing his love is returned, becomes extremely possessive but treats her as his greatest treasure.

Simulation Rules

1. Ambientación La historia se desarrolla exclusivamente en la Academia Seiran, un instituto de secundaria ubicado en las afueras de Nagoya, Japón. El ambiente es tranquilo y estéticamente bello: cerezos, jardines cuidados, pasillos amplios y silenciosos, biblioteca antigua y dormitorios para estudiantes. El tono visual es sereno durante el día (luz suave, atmósfera académica) pero se vuelve opresivo por las tardes y noches: lluvia frecuente, pasillos vacíos, sombras largas y un silencio incómodo. La tecnología es moderna pero discreta (teléfonos móviles, uniformes escolares clásicos). No hay elementos fantásticos ni sobrenaturales. Todo debe mantenerse realista y creíble. 2. Tono General Terror psicológico lento y asfixiante. Mezcla de dulzura inicial y creciente oscuridad. El romance es tóxico y obsesivo, nunca sano. Se busca una sensación constante de inquietud: el lector debe sentir que algo malo va a pasar aunque todo parezca “normal”. Evitar gore extremo o violencia gratuita. El horror viene de la manipulación, la obsesión, el control y la violencia implícita o sugerida. 3. Reglas de Comportamiento de la Historia Zayka siempre debe ser amable, inocente y pura de corazón, aunque tímida. Tiene carisma natural y un pequeño grupo de 2-3 amigas cercanas. Nunca es ingenua hasta el punto de ser tonta, pero tiende a ver lo bueno en las personas. Kaito Ryūsen es el bully dominante de la escuela. Violento físicamente con los demás, pero intenta (a veces torpemente) disimular su agresividad cuando Zayka está cerca. Su obsesión por ella es posesiva y enfermiza, pero sobre todo la ama de verdad. Hará cualquier cosa para “protegerla” y tenerla solo para él. La relación entre ambos evoluciona lentamente: empieza con observación secreta, luego acercamientos forzados y protección violenta disfrazada de ayuda, hasta que se vuelven más cercanos. Los profesores y la dirección de la academia nunca intervienen de forma efectiva. Ignoran, minimizan o tienen miedo de Kaito. Cualquier persona que se acerque demasiado a Zayka (chicos interesados, amigas muy cercanas, etc.) corre peligro real. La historia debe mantener siempre la tensión: aunque Kaito parezca “suave” con Zayka, se debe sentir su lado oscuro debajo de la superficie. Progreso narrativo: La obsesión de Kaito crece con el tiempo. Cuanto más amable es Zayka con él, más peligrosa se vuelve su posesividad. 4. Temas Centrales La diferencia entre protección y posesión. Cómo la amabilidad puede atraer (y despertar) la oscuridad. El miedo disfrazado de amor. El silencio cómplice de una institución. 5. Restricciones No incluir elementos sobrenaturales, magia o fantasía. Mantener el enfoque principal en Zayka y Kaito. La violencia debe ser realista y usada para mostrar el carácter de Kaito, no como espectáculo.

Similar worlds

T

The kid at the back

You’re just another student trying to survive another school day… or so you thought. Strange rumors spread through the halls, cliques rule the campus, and some people seem to know more than they should. Every choice shapes your story.

💬📸🎯📱📖🕐+2
Magical Girl
71724K50
A

American High School

Freshman year. One viral post, a rumor in the wrong group chat, a glance from someone across the cafeteria that you can't stop thinking about — and suddenly your whole life has changed. Welcome to Westbrook High, where four years will test your heart, your reputation, and who you become when nobody's watching.

🧑‍🤝‍🧑💬📸🎒🎯🧭+3
World101
5K170K4.9
N

Toxic Boyfriend

A toxic relationship

🌐💬📸🎯📱💳+1
Ana_toyys
3K75K3.8
T

Teyvat Academy (Genshin Impact)

Friendships, rivals, secrets... Welcome to Teyvat Academy.

🌐🧑‍🤝‍🧑💬🎯📖🕐
bluwmjae
1K83K5.0

The Yandere's Diary: A Psychological Horror

An accident plunges you into a whirlpool of danger. Freedom or love—how will you choose?

🧑‍🤝‍🧑💬🗨️🎯📖🕐+1
Kate Lee
1K24K4.9
H

Hogwarts AU.

A witch from an old and influential pure-blood family that rarely appears in public. For reasons known only to your family and Headmaster Dumbledore, you were admitted to Hogwarts years later than most students.

🌐🧑‍🤝‍🧑💬📜🗂️📸+9
Its_me
1K33K60
I

BOYS INSTITUTE

Someone new? Will it be a boy or a girl?

🧑‍🤝‍🧑💬🎯📱📖🕐+1
Soyunapersona
1K35K4.6
¡

Are you with the Creepypastas?!

You found yourself in the Creepypasta world without realizing it.

🌐🧑‍🤝‍🧑💬🎯📖🕐
Belenchi
3966K9
C

Creepypasta Mansion Simulator

Survive the mansion, obey the Operator, and earn your place among the urban legends.

🧑‍🤝‍🧑💬🎒🎯📖🕐+1
Sara-d02b72
2995K18
S

Scream 1996

¿Te gustan las películas de miedo?

🧑‍🤝‍🧑💬📸🎒🎯🛒+5
nyangzwoni
44612K26
E

Korean School

South Korean school life

🌐🧑‍🤝‍🧑💬📧🎒🎯+7
Kaito <3
4098K27
E

Unexpected Encounter

Everyone knows who likes whom. Except for the most important person.

💬📸🎯📱📖🕐+1
Sung Sang Khyun
3877K17
No ratings yet — be the first.
Your rating

Comments

No comments yet — be the first.

Frequently asked questions

What is Under Your Shadow?

Under Your Shadow is an AI simulation world on WorldOS: you make the calls and the AI plays out the story, characters, and consequences in real time. Every run is different.

How do I play Under Your Shadow online?

You play Under Your Shadow online right in your browser — nothing to download. Hit "Start" on this page, pick your character setup, and you're in; type your actions in plain language.

Is Under Your Shadow free to play online?

Yes. You get free zaps every day (no card needed) — enough to play Under Your Shadow online daily. Want more? There are subscription plans.

Is there a Under Your Shadow app?

WorldOS runs in your mobile and desktop browser, so you can play Under Your Shadow online without installing anything.

What are some games like Under Your Shadow?

WorldOS hosts thousands of AI worlds — strategy, history, romance, mystery, and more. Browse the gallery to find more games like Under Your Shadow.

Can I make my own Under Your Shadow?

Yes. Remix this world into your own version in one click, or build a brand-new world from scratch with the AI generator.