Here is the full list of all 55 Omega Quintet achievements.
Cleared the Training Facility [7th Floor].
Cleared the Training Facility [6th Floor].
Cleared the Training Facility [5th Floor].
Reached the true ending.
Reached the true ending in Advanced mode.
Finished Episode 9.
Maximum damage exceeded 1 million.
Used pair defense 100 times.
Reached the game's ending.
Finished Episode 8.
Finished Episode 7.
Defeated 1,000 enemies.
Finished Episode 6.
Defeated an enemy with an Extra Chain.
Finished Episode 5.
Defeated an enemy with a Harmonic Chain.
Activated Voltage Gauge Level 5 during Live Concert Mode.
Fulfilled a Request.
Activated Live Concert Mode.
Maximum hit count exceeded 300.
Cleared the Training Facility [1st Floor].
Maximum damage exceeded 100,000.
Maximum hit count exceeded 200.
Finished Episode 4.
Generated a Link Bonus.
Finished Episode 3.
Maximum hit count exceeded 100.
Generated a Follow Bonus.
Hunted 10 MADs with Takt's pursuit.
Finished Episode 2.
Defeated 100 enemies.
Succeeded in executing Overkill.
Used the PVS.
Finished Episode 1.
Maximum damage exceeded 10,000.
Defeated an enemy with a Special Skill.
Obtained all trophies.
Cleared the Training Facility [8th Floor].
Cleared the Training Facility [9th Floor].
Cleared the Training Facility [10th Floor].
Cleared the Training Facility [11th Floor].
Cleared the Training Facility [12th Floor].
Otoha reached max affection.
Kyouka reached max affection.
Kanadeko reached max affection.
Nene reached max affection.
Aria reached max affection.
Defeated 10,000 enemies.
Fulfilled 100 Requests.
Used group defense 100 times.
Approval rating exceeded 1 billion.
Completed archives.
Maximized proficiency in all 5 Mic types with any one character.
Finished all Quests.
Defeated Double X.