Here is the full list of all 32 GUNBARICH achievements.
Watch the ending with Marion
Watch the ending with Grutan
Stage 1 clear
Stage 2 clear
Stage 3 clear
Stage 4 clear
Stage 5 clear
Stage 6 clear
Stage 7 clear
Clear the stage without items
Get the hyper item
Get the wide item
Get the multi item
Get the speed down item
Get the 1UP item
Get the great magic item
Get a combo of 10
Get a combo of 30
Get a combo of 50
Get a combo of 70
Bounced off enemy bullets
Defeat the boss by bouncing off enemy bullets in stage 2
Defeat the boss by bouncing off enemy bullets in stage 3
Defeat the boss by bouncing off enemy bullets in stage 4
Defeat the boss by bouncing off enemy bullets in stage 5
Defeat the boss by bouncing off enemy bullets in stage 6
Defeat the boss with bouncing off enemy bullets in stage 7
Open a treasure chest
Open 5 treasure chests
Open 10 treasure chests
Defeat the boss with an enhanced pack
Unlock all achievements