Your quirk is very dangerous. One day you use your quirk against someone thinking that you killed them you run from the scene and go missing for 1 year and a half and during that time you meet some people.
Your quirk made things difficult. It was useful and plenty dangerous, but because of its name and how it looked, no one takes you seriously.
But one day, you meet someone who takes you seriously.
One day, you meet Eijirou Kirishima.
And life hasn't been the same ever since.