It's about a boy who lived in a small house (he was poor) in the corner of a large property owned by a rich family. They were friends and the poor boy was kidnapped bc he said he was the rich boy. The rich boy returns (I think) from overseas or somewhere, maybe college, and they meet again fall in love blah blah blah... And the rich guy sits in front of poor boys parents asking for him. Think the poor boy had black hair and rich had blonde hair (not too sure about this though)

If I'm not mistaken you might be looking for Mad Cinderella.

THANK YOU SO MUCH!! I thought "no way is it by Yamamoto" so I didn't even check when I searched through a bunch of manga