A new educational comic created by Kim Kelly—a YouTuber with 1.3 million followers—and the team behind the hit webtoon Hold On to Your Sanity (writer Shin Tae-hoon).
Fully reflects the 2025 science curriculum—just follow the story and the textbook concepts stick in your head.
A high-quality science primer supervised and recommended by the KAIST Institute for Science Gifted Education.
Carefully selected 12 core physics topics every elementary student should know, reinforced with fact pages and quizzes.
Covers biology, earth science, physics, and now chemistry—complete mastery of elementary science!

This series include:
Weather Fairy Kim Kelly 1: The Life Cycle Queen and the Garden in Crisis
Weather Fairy Kim Kelly 2: The Legend Reawakened — The Volcano Golem
Weather Fairy Kim Kelly 3: The Sacred Waterfall That Ran Dry
Weather Fairy Kim Kelly 4: Villain Momo's State-Change Weapons

The villain fairy Momo is back—with a state‑change weapon!

Hidden from human eyes, a group of fairies travel between the fairy world and our world, managing the weather. Sunny (sunshine), Qua (rain), Windy (wind), and Shasha (snow) work hard each day to keep the weather in check. Meanwhile, Kim Kelly—a third‑grader at Sunny Elementary who gained mysterious powers after swallowing Sunny's magical "Sunny Stick"—teams up with the weather fairies on thrilling adventures.

After returning from the fairy world, Kelly is buried in midterm exam prep, living a busy but fulfilling life. Then, in the middle of an otherwise ordinary day, Momo—the dark‑cloud fairy who disappeared after the Sacred Falls incident—reappears. Having failed to obtain a magic stone last time, Momo now carries a special "State‑Change Weapon," aiming to steal Kelly's powers. In the face of this mysterious weapon that can turn solids into liquids and liquids into gases, Kelly and her fairy friends—Sunny, Qua, Windy, and Shasha—find themselves in grave danger. What's more, a cool‑headed and meticulous new villain fairy, Nova, joins forces with Momo. Can Kelly and the weather fairies grasp the principles of chemistry, stop Momo's weapon, and protect the fairy world?

A world heading toward its climax, and even more lovable characters!

The writing and artwork for Weather Fairy Kim Kelly 4: Villain Momo's State‑Change Weapon come from Thunder Studio—a webtoon and educational‑comic studio founded by Shin Tae‑hoon, the creator of the hit webtoon Hold On to Your Sanity. As the series progresses, its world‑building grows richer, and the endearing weather fairies, along with villains from Momo to Nova with their distinct personalities, deliver whimsical plots and humor that will make both kids and adults laugh out loud. What truly stands out is the vivid characterization—every expression and movement is brought to life with great care. With an engaging story, adorable characters, solid educational content, and a cute bonus gift, this volume completes the "Physics, Chemistry, Biology, Earth Science" series, offering young readers yet another unique reading experience.

Kim Kelly (Kim Eun-young) – Click to follow this author.

She creates comedy YouTube videos with the goal of making students laugh. Drawing on her long experience as an elementary school teacher, she captures the real-life traits and quirks of her students in her content, which resonates with many young viewers. Now, she strives to produce comedy videos with wholesome themes and language, matching the love she receives. Beyond simple laughs, she hopes to offer children inspiration and life lessons. Her latest work is Kim Kelly's Mystery Mart 1.

Features of This Book ··········· 4
Characters ··········· 8

1. Back to Everyday Life ··········· 10

2. Kelly's Studying? Really? ··········· 18
Kelly's Curiosity Corner – What Are Objects and What Is Matter? ··········· 27

3. Bubble-Bubble Ramyun ··········· 28
Kelly's Curiosity Corner – Where Did the Water Go? ··········· 37

4. Dark Clouds Rolling In ··········· 38

5. Sweet and Cool Iced Tea! ··········· 46
Kelly's Curiosity Corner – Where Did the Sugar Go? ··········· 53

6. Emergency! Fairy Planes Spilling Everywhere ··········· 54
Kelly's Curiosity Corner – Ecosystem Damage from Acidification? ··········· 65

7. Withered Garden and the Sudden Downpour ··········· 66
Kelly's Curiosity Corner – What Are Indicators? ··········· 75

8. Kelly's Chemistry Study Notes ··········· 76
Kelly's Curiosity Corner – What Happens When You Mix an Acidic Solution and a Basic Solution? ··········· 81

9. Why Drinking Fountain Water Is Clean ··········· 82
Kelly's Curiosity Corner – How Do We Get Clean Water? ··········· 91

10. Stop the Floating Trash! ··········· 92
Kelly's Curiosity Corner – How to Separate Particles of Different Sizes ··········· 103

11. The Villain Fairy Is Back – Momo ··········· 104
Kelly's Curiosity Corner – What Are the Three States of Matter? ··········· 121

12. Stop the State-Change Weapon! ··········· 122
Kelly's Curiosity Corner – How Are Solids, Liquids, and Gases Different? ··········· 137

13. The Burned Science Notebook ··········· 138
Kelly's Curiosity Corner – What Is Combustion? ··········· 143

14. The Puffing Kettle ··········· 144
Kelly's Curiosity Corner – How Is Gas Used in Everyday Life? ··········· 155

15. Kelly Floats Up into the Sky ··········· 156

16. A Perfect Score! ··········· 162

Kelly's Curiosity Quiz ··········· 168