Well, he might be really confused at first. Manga has a very different art style and storytelling approach compared to what he's used to in the wizarding world. He could be intrigued by the unique characters and fantastical settings in manga fanfiction, perhaps even finding some similarities to his own magical experiences.
If Harry Potter found manga fanfiction, he might try to understand the cultural context behind it. Manga often comes from a different cultural background than the British wizarding world he inhabits. He could be fascinated by the different types of magic or powers depicted in the fanfiction, and might even start to think about how those concepts could be applied in his own world. For example, some manga have characters with the ability to control elements in a very different way from how wizards in his world do magic. He could also be a bit put off by how different the relationships between characters are sometimes portrayed in manga, as they can be much more complex or emotional in a different way.
Chapter 440, "You Know Fengshui Array?!", is the clearest early answer because it turns Shang Shuyue's situation into a concrete plot event.
Chapter 433, "The Young Master Has His Own Ideas", is the clearest early answer because it turns Team's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Since Jiang Yan and his group left, the house had become much colder.
Chapter 186, "The Goddess Who Can't Stand the Smell of Pig Manure", is the clearest early answer because it turns Director Sun's situation into a concrete plot event. The chapter gives readers a real answer by opening on Seeing Wen Jiaojiao bravely entering the pigsty, Jiang Yan couldn't...
Chapter 384, "To celebrate my selection, live streaming tomorrow night.", is the clearest early answer because it turns Wilderness Survival's situation into a concrete plot event. It opens with How much funding are you expecting?" After reviewing the documents,...
Chapter 242, "Jiang Yan's Dazzling Transformation Journey", is the clearest early answer because it pushes Jiang Yan into a new phase or setting. The chapter turns that into something concrete by moving from Just when Jiang Yan called to heaven and earth in vain, he looked up...
Chapter 333, "The Clothing Design Room", is the clearest early answer because it turns Lin Manru's situation into a concrete plot event. Early on, [LOL, the little brother turns out to be socially anxious too, he.... By the end, You've been cooped up in your room all week staring at this book;
Chapter 492, "Rewarding You with Some Wild Vegetables", is the clearest early answer because the buildup finally cashes out in a real clash. The chapter turns that into something concrete by moving from Upon hearing the words, Jiang Cheng's face instantly turned pale.
Chapter 414, "The White Knife Goes In, The Red Knife Comes Out", is the clearest early answer because it turns Guan Xiong's situation into a concrete plot event. The chapter gives readers a real answer by opening on Third Master really lives up to his reputation; his skills are...
Chapter 627, "Definitely Not an Accident", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from He looked at the sinister smile lingering in Jiang Li's eyes, then at...
Chapter 391, "Has another top celebrity had a scandal?", is the clearest early answer because it turns Beijing Film Academy's situation into a concrete plot event. The chapter turns that into something concrete by moving from You were born in a rural area, not exactly poor, but not particularly...