Here is the full list of all 19 LoveKami -Useless Goddess- achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
Open sound screen.
Open the gallery.
Clear Maika's route.
Clear all routes.
View 100% of event scenes.
View 80% of event scenes.
Clear Inori's route.
Complete first playthrough.
Clear Akane's route.
View 60% of event scenes.
View the ending movie.
View 40% of event scenes.
Finish the common route.
View 20% of event scenes.
View the opening movie.
View the first event scene.
The first tip displays.
Begin the game.
Open the config screen.