Teru Momijiyama, better known as Shy, is the main protagonist of the manga series, SHY. Teru is a middle school student who also moonlights as Japan’s Hero, SHY. Her special power, Flame is catalyzed through the Heart Conversion Bracelets that convert her Heart spirit into her flame power.

Shy
Around the middle of the 21st century, all war on Earth ceased. The sudden widespread appearance of "Heroes," people with supernatural powers who wish only for peace, has drastically transformed the world. In a world where the Heroes of each country work to maintain this newfound peace, the one protecting Japan is a young girl named Shy who is...cripplingly shy.

(from Fandom Shy Wiki)