Both are dramas about REAL life issues. And in IS Haru is very similar character to Last Friend's Ruka.
IS - Otoko Demo Onna Demo Nai Sei (2011)
Similars
Both involve the life of a person.... Born to be neither a male..nor a female.. or maybe both?! He/she is the main protagonist in it.
Both dramas touch on gender identity issues. What is the line between males and females. IS is a more light-hearted drama where it addresses on coping with daily life.