Here is the full list of all 21 The Tenth Line achievements.
Call an assist character to attack.
Win a match of Quad Pro Quo.
Win a battle.
Deal 20,000 total damage in one Attack Phase.
Conquer the Champion's Gnaw.
Complete the quest Cold Comfort.
Complete the quest Reeking Rematch.
Complete the quest The Truth.
Launch a foe in the world with an attack.
Reach a 3-digit value in all four stats on any one character.
Deal 1 million total damage.
Collect every Quad Pro Quo card.
Throw 1000 knives in battle as Rik.
Complete Chapter 1.
Complete Chapter 2.
Complete Chapter 3.
Complete Chapter 4.
Complete Chapter 5.
Carry out a super attack with a party member.
Complete a Treasure Hunt quest.
Recruit every dracon assist character.