Here is the full list of all 20 Kare wa Kanojo achievements.
Find the secret code in the game
Get a kiss from Rika
Help Rika with the festival
Grope Rika (accidentally)
Get a kiss from Nanami
Prank your friends with Nanami
Complete Nanami's route
Choose to game at the beginning of the game.
Get a kiss from Sakura
Find the truth about Sakura
Help Sakura tell the truth to Nanami
Complete Sakura's route
Tell Sakura the truth about the yukata
Finish the game for the first time
Complete Rika's route
Complete the fifth chapter
Complete the fourth chapter
Complete the third chapter
Complete the second chapter
Complete the first chapter