Here is the full list of all 12 A traveler's photo album achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Unlock the angel
Unlock the Tree demon
Unlock the Bee girl
Unlock the Nekomusume
Unlock the Fairy girl
Unlock the girl
Unlock the flower fairy
Unlock the Butterfly Girl
Unlock the maid
Unlock the Firefly spirit
Unlock the Bunny Girl
Unlock the mermaid