I Have A Dragon's Heart is a Manga/Manhwa/Manhua in english language, Manhwa series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Sharon, a warrior who defeated a vicious dragon a thousand years ago. One day, an unidentified man appears in front of Aru, who grew up longing for Sharon. what? Are you that terrifying dragon? Besides, I'm that hero?! A cute and sad romance fantasy of a dragon and a hero who reunited after a thousand years!