In the first episode of I Got a Cheat Skill in Another World and Became Unrivaled in The Real World, Too, short Iseleve ("I acquired a cheat skill in another world and became unrivaled in the real world too"), we are introduced to the protagonist Yuuya Tenjou. Due to his appearance and the way he is treated by his family and classmates, he has always struggled with his self-esteem. When Yuuya inherits his late grandfather's house, he discovers a mysterious door that leads to another world, where he gains a variety of abilities and skills.

The episode highlights Yuuya's harsh life, including scenes where he is bullied and his efforts to stand up for others. For example, he bravely confronts a group of men harassing a girl, proving his courage and kindness.

While exploring the room with the door to the other world, Yuuya comes across numerous artifacts and weapons. By becoming their owner, he acquires various skills, such as swordsmanship and language comprehension, which enhance his abilities.

In the other world, Yuuya encounters a terrifying monster like a Bloody Ogre. After defeating it, he obtains various items that he can exchange for money in his own world. Upon returning, Yuuya notices changes in his appearance but continues to focus on understanding his new powers.

Throughout the episode, Yuuya discovers several unusual plants with unique properties, such as the healing herb, the superpower tomato, the invincible kabocha, the great wisdom daikon, and the divine speed potato. His initial confusion gradually turns into curiosity as he adapts to this new world.

In a decisive moment, Yuuya encounters a powerful Hell Slime and defeats it. As a result, he obtains another rare item, the Black Moon Necklace, which increases his level and grants him the "Presence Detection" ability. Despite his growing strength, Yuuya remains aware of his responsibilities in the real world and decides to buy a new school uniform.

When Yuuya returns to school, his classmates and siblings are astonished by his changed appearance. They wonder if he is a model or an exchange student and can no longer recognize the person they once knew. The episode ends with a mysterious girl identifying Yuuya by his name, leaving the viewers eager for further developments.