Here is the full list of all 30 Sayonara Umihara Kawase achievements.
Play everything in the Sound Gallery.
Clear Survival Challenge.
Play Survival Challenge.
Clear all doors.
Clear Tadpole 2.
Unlock all Stages.
Clear Crab 2.
Acquire 45 backpacks.
Clear Balloonfish.
Play your own Replay 10 times.
Watch all Stage Tutorials.
Fail a Stage 50 times.
Clear Crab.
Acquire 30 backpacks.
Use all characters.
Clear Sayonara UmiharaKawase +.
Clear Tadpole.
Catch a Tadpole.
Fail a Stage 20 times.
Acquire 10 backpacks.
Browse the Illustration Gallery.
Clear the second door in a Stage.
Fail a Stage while holding a backpack.
Acquire two backpacks at the same time.
Check all Walkthrough Tips in the Gallery.
Browse the Sound Gallery.
Watch the Stage Tutorial of a Stage you've cleared.
Acquire a backpack.
Clear all routes on Survival Challenge.
View everything in the Illustration Gallery.