From Today On, I’m a Boy is a Manga/Manhwa/Manhua in english language, Action 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

“If nobody notices that you are a girl until we graduate, I will give you a billion won.”
“I’m in.”
The bet was on. Will Shiru be able to hide her identity until she graduates?!