Here is the full list of all 43 Sword Art Online: Lost Song trophies - there are 23 bronze, 18 silver, 1 gold and 1 platinum.
Collect 50 different accessories.
Complete a total of 10 Side Quests, Extra Quests, and/or Multiplayer Quests with a party consisting of any single character.
Raise a single Magic Skill or Special Skill to level 500.
Complete a total of 100 Extra Quests and/or Multiplayer Quests.
Raise a single Sword Skill to level 500. *OSS included.
Complete a total of 100 Side Quests.
Create a party that includes your own custom character.
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, Klein, and Agil.
Obtain Excalibur.
Collect 100 different weapons, not including shields.
Complete a Side Quest, Extra Quest, or Multiplayer Quest with a party consisting of Kirito and Asuna.
Complete Asuna's side story. "Stay with me forever, Asuna."
Befriend Sumeragi.
Go to the festival with all the game's heroines. "This is a sweet scoop!"
Complete Lisbeth's side story. "We're going to forge a lot of memories together, whether you like it or not."
Complete all main story chapters. "We still have a lot more gaming left to do!"
Reach the story chapter "The Two Idols."
Complete Silica's side story. "I won't tell anyone what happened here today."
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."
Reach the story chapter "The Dark World."
Defeat 1,000 enemies over the course of the game.
Have more than 1,000,000 Yuld.
Reach the story chapter "Intertwined Desires."
Complete an Extra Quest without taking damage.
Reach the story chapter "Lies."
Reach the story chapter "Battle of the Knights of the Tri-blade."
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 Leafa's side story. "I hope that I'll always get along with Sugu."
Reach the story chapter "A Paradox of Light and Darkness."
Reach the story chapter "The Redhead in the Shadows."
Defeat 5 or more enemies at the same time with a single attack.
Reach the story chapter "The Youthful Goddess."
Complete your first Side Quest.
Reach the story chapter "The World of the Black Fairies."
Reach the story chapter "Fairies in the Sky."
Log into ALfheim Online.
Earn all trophies. "You are an excellent fighter. The best I have ever seen."
Raise a weapon's Enhancement Level to its maximum.
Raise Asuna, Yuuki, Rain, and Sumeragi's OSS to level 100.
Learn every possible Sword Skill, Magic Skill, and Special Skill for a single character.