Here is the full list of all 18 RUKIMIN's Disappointing Adventure! achievements.
Clear with less than 5 deaths
Meet a macho hero.
Completed the mission.
Died 100 times
Beat SUZUKO.
Completed faster than 10 minutes.
Escaped from the wall.
Game over on the game select scene.
Returned to the starting point.
Finished the tutorial.
Game over on the title screen.
Overflowing from the screen.
Died once.
Died 10 times
Died 50 times
Eat rice balls
Beat Mr. Bomber.
Found white asparagus.