Here is the full list of all 24 Learn Japanese To Survive! Katakana War achievements.
Clear the game.
Complete all 20 side quests.
Obtain the ultimate sword.
Complete 15 side quests.
Complete lesson 10.
Complete lesson 9.
Complete lesson 8.
Complete lesson 7.
Complete 10 side quests.
Complete lesson 6.
Maximize all character's affection levels.
Complete lesson 5.
Unlock the potential of corn soup.
Visit the Challenge Castle.
Maximize a character's affection level.
Complete 5 side quests.
Complete lesson 4.
Try 3 different types of seafood.
Complete lesson 3.
Unlock the power of the Crystarium
View a character's affection event.
Complete a side quest.
Complete lesson 2.
Complete lesson 1.