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