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