Helpppp

I read this manga but i forgot the name and im going crazy cause i wanna read it again. If u want to help, the manga is about a guy A and another guy b the guy b has like a bet that if the guy a falls inlove with him he gets something then after that the guy a falls inlove with guy b then, the guy a found out it was just a bet so he be sad, then guy b understood that he fell for guy a. Thats like the plot it it contains like a secret key and stuff. Idk if its a short one i've already forgot. :*(

Please help?!! I've gone nutsss..