Warning: SPOILERS for chapter #175 of One-Punch Man
Fubuki, one of 's most popular heroes has a dark side that makes her more twisted than any monster in the series. A flashback detailing Fubuki's past relationship with Psykos shows that the Blizzard of Hell's ruthless behavior made her even crueler than the future leader of the Monster Association.
, aka Tornado of Terror, the powerful and feared S-Class Rank 2 hero. While Fubuki is much weaker than her sister, she made up for it by creating a vast group of underlings among B-Class heroes, the Fubuki group. Fubuki's inferiority complex towards her sister led her to develop a cold-hearted and ambitious personality. She secured her position as B-Class Rank 1 hero and maintained it with ruthless tactics, including sending her underlings to beat up new heroes. However, her deeply changed Fubuki, inspiring her to overcome her complex and aspire to become a better hero.
A flashback in chapter #175 of shows that before meeting Saitama, Fubuki was even worse than what readers believed. Back in high school, Fubuki was the president of a club called "Society for Supernatural Research", with Psykos as her vice. When Psykos proposed an outrageous plan to exterminate "normal" humans (which foreshadowed her future plans as ), Fubuki decided to stop her and sealed her psychic powers away. However, she did not do it out of goodwill. If Psykos' plan succeeded, Fubuki would have been deprived of the "losers" of the world, the inferior people she wanted to rule over after she surpassed her sister and stood at the top.
As Fubuki herself admits in the present, she was a completely self-centered person. Rather than being concerned about the victims of Psykos' plan, she only thought about how that would affect her own . Even worse, she did not even try to persuade Psykos or any other peaceful solution, she just went ahead and messed with her mind to lock her out of her powers. It's an incredibly cruel thing to do, even to someone as deranged as Psykos, and it just shows how ruthless and cold-hearted Fubuki was, even as a teenager.
Over time, Fubuki's heroic nature took over. She remains a charismatic leader, but she now cares more about the members of the Fubuki group. During the battle against the Monster Association, she showed selfless behavior more than once, to the point of even being willing to sacrifice herself. This goes to prove just (even without actively trying to do so), as before their meeting, Fubuki was a self-centered woman who could be more cruel and ruthless than any monster in .
The latest chapter of is available through Viz Media.