Here is the full list of all 14 Lovely Planet achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Unlock All Stars (Village)
Visit the Shrine of Lovely Planet
Find the Graves (Village)
Find the Hungry Samurai (Village)
Unlock All Stars (City)
Parry Projectile at Right Angles
Shoot Yourself
Unlock All Stars (Forest)
Unlock All Stars (Swamp)
Unlock All Stars (Mountains)
Collect All Gun Colors
Find All Hidden Secrets
Find the Dagger with the Pearl Inlay (Forest)
Drink the Sake (Swamp)