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