Shy

It's a time of superheroes. Every superhero represents a nation. This is Shy. She represents Japan, but like her Name implies she is very shy and have social anxiety. She helps people wherever she can. But she tends to doubt herself if she fails to help. Even resulting in loosing her powers temporarily because of her doubts. When she's not "Shy" she is the 14 year old schoolgirl Teru Momijiyama. You're a new superhero (choose gender, nation and nickname) and you meet her at the preparation for an important mission.