I recently watched Good Morning Call (season 1&2), Itazura na Kiss (season 1&2), and A Girl and Three Sweethearts.
I’m looking for similar Japanese dramas. :)
It's not really a Japanese drama, but Attention, Love! has themes of unrequited love and it's pretty enjoyable :)
Japan dramas with unrequited love
minamikun no koiboto
Kahogo no kahogo(kinda)
Kdramas- to the beautiful you
Not really japanese drama but check put the korean drama Because Its the First Time, it has one of the sweetest unreguited love story of thr main character.
Also check Taiwanese movie Apple of My Eye