Here is the full list of all 15 Love n Dream achievements.
Obtain all collectible items
Complete Inomi's story
Obtain all hearts
Complete Honatsu's story
Complete Maritsuki's story
Complete Yasuna's story
Complete Tamami's story
Obtain 30 or more hearts
Obtain 20 or more collectible items
Complete Tofumi's story
Complete Misatsune's story
Complete the first level
Record your first heart
Poke 200 times
Record your first collectible item