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.
Unlock the potential of corn soup.
Complete 15 side quests.
Complete lesson 10.
Complete lesson 9.
Unlock the power of the Crystarium
Complete lesson 8.
Complete lesson 7.
Complete 10 side quests.
Complete lesson 6.
Try 3 different types of seafood.
Maximize a character's affection level.
Complete lesson 5.
Visit the Challenge Castle.
Complete 5 side quests.
Complete lesson 4.
Complete lesson 3.
View a character's affection event.
Complete a side quest.
Complete lesson 2.
Complete lesson 1.