Hello lovely people

I'm looking for a reincarnation novel in which the mc, while still a child, meets the country's prince and teaches him stuff, including english to be used as a secret code in the army. I think he looks girly because if I'm not mistaken there was a part when he used his medicine knowledge while disguised/thought of as a girl. I also think every time the prince wants to meet him he puts up posters?

oh yeah, it's probably a shounen ai/yaoi

thanks

I'd like to know which one this is too.

you probably shouldn't be necroing posts, but I found the novel a while ago. It's called Forsaken Ballad and you can read it here: http://pandamonium-chaos.deviantart.com/gallery/51149341/For saken-Ballad?offset=48