Mahou Shoujo Jihen

Every child has a dream job, and for Hiromi Sakura, it was being a hero like his favorite color-coded defenders of justice. Unfortunately, not all wishes come true, and now he's forever stuck with a miserable desk job—until one evening, when he steps up to save a little girl's life. With his newfound courage and strength to fight evil, Hiromi transforms...into a magical girl?!

(Source: Yen Press)