Both are about a group of friends who have different love stories. The plot also includes their professional adventures, but this is not an overwhelming part of these dramas. In both, the characters make important life decisions. Both dramas have a rather positive overtone, they are not depressing.
"Koi Nante, Honki de Yatte Do Suru no?" it's about some older characters than those in "Manatsu no Cinderella".