While Yagate Kimi ni Naru goes more in-depth, both involve the theme of using a mask socially to cover your inner insecurities.
Same high-school setting, same "most popular star student" main girl, same theme of only revealing your true self to each other, and both shoujo-ai.
Similar MC : Misono and Haruka are both popular students,while Yuri and Misuzu are both loner,through Yuri is seen as a delinquent.
Plot are built on the same line through Fragtime has some supernatural things.
Both of them are good shojo-ai.
Both manga have a very enjoyable story, some comedy, interesting characters and the relationship between the girls is very well developed. If you enjoyed reading Girl Friends, you'll just love Zenryaku!