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