Here is the full list of all 43 Sword Art Online: Lost Song achievements.
Earn all trophies. "You are an excellent fighter. The best I have ever seen."
Learn every possible Sword Skill, Magic Skill, and Special Skill for a single character.
Complete a total of 100 Extra Quests and/or Multiplayer Quests.
Obtain Excalibur.
Raise Asuna, Yuuki, Rain, and Sumeragi's OSS to level 100.
Raise a weapon's Enhancement Level to its maximum.
Collect 100 different weapons, not including shields.
Complete an Extra Quest without taking damage.
Complete Asuna's side story. "Stay with me forever, Asuna."
Befriend Sumeragi.
Complete Lisbeth's side story. "We're going to forge a lot of memories together, whether you like it or not."
Go to the festival with all the game's heroines. "This's a sweet scoop!"
Complete all main story chapters. "We still have a lot more gaming left to do!"
Reach the story chapter "The Two Idols."
Complete Sinon's side story. "Sinon is an indispensable part of this team, and an important friend."
Reach the story chapter "The Twilight of the Gods."
Complete a total of 100 side quests.
Raise a single Sword Skill to level 500. *OSS included.
Collect 50 different accessories.
Complete Silica's side story. "I won't tell anyone what happened here today."
Reach the story chapter "The Dark World."
Raise a single Magic Skill or Special Skill to level 500.
Have more than 1,000,000 Yuld.
Reach the story chapter "Intertwined Desires."
Create a party that includes your own custom character.
Reach the story chapter "Lies."
Defeat 1,000 enemies over the course of the game.
Reach the story chapter "Battle of the Knights of the Tri-blade."
Reach the story chapter "A Paradox of Light and Darkness."
Reach the story chapter "The Red-head in the Shadows."
Complete Leafa's side story. "I hope that I'll always get along with Sugu."
Complete a side quest, Extra Quest, or Multiplayer quest with a party consisting of Kirito, Klein, and Agil.
Reach the story chapter "The Youthful Goddess."
Complete a side quest, Extra Quest, or Multiplayer Quest with a party consisting of Silica, Lisbeth, and Leafa.
Complete a side quest, Extra Quest, or Multiplayer Quest with a party consisting of Kirito and Asuna.
Resurrect a party member who has become a Remain Light.
Have the character you are controlling reach 0 HP and become a Remain Light.
Complete a total of 10 side quests, Extra Quests, and/or Multiplayer Quests with a party consisting of any single character.
Complete your first side quest.
Defeat 5 or more enemies at the same time with a single attack.
Reach the story chapter "The World of the Black Fairies."
Reach the story chapter "Fairies in the Sky."
Log into ALfheim Online.