WARNING: The following contains spoilers for My Hero Academia Chapter 336, "Villains” by Kohei Horikoshi, Caleb Cook and John Hunt, available now in English from Viz Media.
The U.A. traitor subplot has been lingering in the minds of fans of My Hero Academia for years now, and Chapter 335 of the manga ended on what many fans believed to be the reveal of the traitor's identity. Theories have run rampant over the years, from Aoyama's bizarre behavior to Monoma's over-the-top disdain for Class 1-A. After Chapter 335 ends with All For One's words about having friends to spare in a panel featuring Toru Hagakure, Chapter 336 reveals that this was a misdirect and that Yuga Aoyama is indeed the traitor. However, after the previous chapter's ending, fans around the globe had no issue accepting Hagakure as the traitor, and the idea does make a surprising amount of sense.
The idea of Toru Hagakure being the traitor has a great deal of merit to it when examining the character's history. After the League of Villains attacked during the USJ Incident as well as the Forest Training Arc, U.A.'s teachers and principal began to suspect they had a traitor in their midst. Class 1-A's presence at each location, as well as the locations themselves, was not known to anyone outside the school before the League arrived in each instance, meaning someone had to be feeding them the information. In the days prior to the Forest Training Arc, it was Hagakure's idea for Class 1-A to head to the mall where Deku was subsequently confronted by Shigaraki, who'd been waiting for him.
Although it's obvious, it must be said: an invisibility Quirk is perfect for a spy. Hagakure's Quirk has long been a topic of debate, as her Quirk is nearly useless for hero work, considering her power is just that she's invisible. It's never made much sense that she could have made it to Class 1-A with such a limited Quirk, especially compared to powerful Quirks like those held by 1-B's Monoma or Shinso, who failed the entrance exam altogether. It's not clear how she could have wound up in 1-A if she didn't deserve it, but All For One's influence is wide-reaching and it's possible he could orchestrate an underserving student's acceptance into U.A.
The fact that Hagakure has developed the ability to refract the light that passes through her body could be interpreted as an indication that she is lying about the extent of her Quirk. After all, just being invisible 24/7 shouldn't correlate to manipulating light, unless manipulating light is her true Quirk. If Hagakure can become invisible at will, it would explain why she so frequently exhibits distress at undressing around people, almost as though she's forgotten that she's invisible. It's even possible that she's not actually a kid, which would explain her theoretical need to lie about her Quirk and stay invisible at all times.
In the context of being a traitor, a lot of Hagakure's past behavior becomes suspicious. After the USJ Incident, she reveals that she was near Shoto during the fighting, much to Shoto's surprise, as the young Todoroki mentions he could have frozen her not knowing she was there. That Hagakure would not alert her comrades to her presence, especially Shoto, who uses large-scale attacks, could either be a lack of intelligence on her part or part of a scheme to cause further chaos during the battle. It'd even possible she lied about having been near Todoroki at all, using her invisibility to remain unaccounted for during the fighting to look for ways to help the villains.
Hagakure has a decent alibi during the Forest Training Arc, having been hospitalized as a result of the poison used by the League of Villains during the Forest Training Arc. Although, what better way to avoid suspicion than to be a victim of the attack? Hagakure has been a little sketchy from the start, as very little has been revealed about her personal history, unlike the rest of her classmates. In a series where every character is the main character, Hagakure spends less time in the spotlight than anyone. Frankly, quite a bit adds up to support the idea of Hagakure being the traitor, so it's almost disappointing to learn that Aoyama has been the traitor this whole time.
