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