Mount Lady is a character from the anime and manga My Hero Academia.
Her real name is Yu Takeyama, and she is part of a universe where people are born with unique superpowers known as "Quirks", which they use to become superheroes or super-villains.
Yu's Quirk is the ability to grow to giant size, being able to grow to the size of a skyscraper. She protects the innocent and fights the forces of evil as the giantess superheroine Mount Lady.
Mount Lady deeply enjoys being a giantess, getting an almost orgasmic thrill from being giant-sized or growing to giant size. She also enjoys the popularity that comes with being a famous superheroine. Despite this, she has a noble heart and is always willing to fight against injustice and crime.
Unlike most other superheroes in the setting, Mount Lady is a "Pro" superheroine, meaning she is a veteran superheroine that has long since graduated from the titular superhero academy.
Mount Lady is somewhat vain and idolizing, however she is a good person at heart. She is always careful and worried about her powers, namely destroying nearby buildings or harming innocent people.