Kang Seulgi came from a family of supers. So, since a young age she had been exposed to 2 main types of powers, earth and water manipulation.
Seulgi was categorised as a late bloomer by her family since her powers weren't unlocked until the age of 12. However, it wasn't how long it took for her to expose her powers that made them shocked - it was the element that she was gifted with. The element of fire.
After her true powers were discovered and coming to terms that they didn't have the method to control her powers, Seulgi was sent off to Hero High in hopes that she will be able to learn and come to terms with her powers.

Seulgi had always known she was a fire element but could never accept the fact she was the only fire controller in the family so for years, Seulgi forced her powers to be suppressed in hopes it would go away. It only made things worse as Seulgi's physical health took a toll from the constant force she had to put in whenever she held back her powers from igniting. This has caused her powers to become unstable due to the long period of being dormant. Seulgi has to wear fire proof gloves to prevent sudden ignitions and has to keep her emotions in check. The stronger her emotions, the harder it is for her to control her fires.

As a super hero, Seulgi is known as Hestia - named after the Greek Goddess of hearth.