In a medieval fantasy world, Kuzuno Sekai is in prison. On a whim, he instantly steals the panties of the girl in the next cell, then after teasing her about the teddy bear design on them, returns them just as quickly. Shocked, she asks how he did that, and he says he made a duplicate of the key and can leave whenever he wants. He steals some apples and offers one to her. She introduces herself as Niña, who was arrested for thievery, and asks why he's staying in the prison if he can leave.
Sekai explains he is from the modern world. One day, he was humiliated when an embarrassing photo of him was uploaded on the Internet. Ostracized by society, he wished to not be in his world anymore and abruptly woke up in this world. With nothing but the clothes on his back and his video game controller, he came to believe he's in a video game world. He played around with the controller and discovered time freezes when he hits Pause and unfreezes when he hits it again. He immediately indulged his hedonistic desires by using this ability to look up girl's skirts and steal food and money. He gets a little carried away describing all the girls he ogled, and an annoyed Niña orders him to move the story along. Anyway, after sleeping in an inn, he woke up and noticed a timer in his field of vision that is counting down from roughly 50 hours. The timer stops when he freezes time, but he worries that if it reaches zero, he might die.
Niña is totally lost, unable to understand his modern terms, but Sekai continues. He explored the city, learning he can read the local language, and decided that if this is a video game, there must be a boss to defeat and get a Stage Clear. He bought a sword (after freezing and ogling the lovely shopkeeper) and went into the woods to practice on small fry. He found a group of evil goblins that just killed a traveler and froze time to easily kill them. He carried the man's corpse into the city and was accused of his murder and sentenced to death.
Niña asks why he would not resist arrest and Sekai says he learned death row inmates are given a chance to earn their freedom by fighting a giant monster in a gladiator arena. No prisoner has ever survived, so he is sure the monster is the boss he must defeat. A guard comes to take Sekai to the arena and he apologizes for not being able to show her his prowess. However, she picked his pocket for his duplicate key and escapes.
Sekai is taken to the arena and given back his sword. He is quickly heckled by the audience for looking weak. The King and his daughter Princess Alicia are in attendance. Alicia is uncomfortable with watching blood sports, but her father says this is part of the royal duties. Sekai is quickly smitten with Alicia's beauty and freezes time just to run over and look up her skirt, then runs back and unfreezes time. He hopes this game ends with him marrying her. Niña sneaks into the audience to watch. The monster is unleashed, a giant sand worm. The sand worm spits acid and he freezes time to dodge it. When he unfreezes time, the acid hits some people in the audience, injuring them. Worried, he freezes time again and tries to stab it, but his sword breaks on contact. Keeping time frozen, he leaves the arena and wanders the city for three days.
Sekai comes back with a higher quality sword called Iron Slayer and attacks the sand worm, but the sword bounces off its body. He realizes it is because he is not strong enough and spends 275 days working out and training, becoming really buff. During this time, he played around with the frozen sand worm and named it Sankichi. Once he is ready, he cuts his hair back to its original length. He did research on sand worms and learned their bodies are heavily armored with very few weak spots, so he just stabs it everywhere. He finally unfreezes time and everyone is shocked because from their perspective, he killed the sand worm in an instant. Alicia is excited and tells her father that Sekai is the Brave, the person destined to defeat the King of Darkness. To Sekai's chagrin, the timer didn't stop, and now he has roughly 43 hours left.
- Get into Jail Free: Sekai brings a dead body in and is accused of murder because he wanted to be arrested and face the kingdom's monster.
- Noodle Incident: Whatever Sekai did to make him a pariah on Earth is not shown to the audience.
- Spectator Casualty: Some people are hurt by the sand worm's acid spit.
- Trial by Combat: How prisoners on death row are judged. They go free if they can beat a monster in an arena.
