Here is the full list of all 29 Fairy Fencer F achievements. It takes around 50-60 hours to unlock all of the achievements on Windows.
You saw Tiara's ending. "You have changed everything for me."
Apollonius joined the party. "I'll become your overseer."
Dealt 100,000 damage. "With this one blow!"
You saw Eryn's ending. "I'm hungry, too!"
Performed 100 Air Combos. "There!"
Fought 500 battles. "Fwoooooosh!"
Maxed your tension 300 times. "I'm fired up!"
Performed 100 Avalanche Attacks. "We're invincible!"
Eryn powered up. "If I decide to get serious, I'm capable of all kinds of things."
Reached level 10 with one of your fairies. "There's still much we don't know about fairies."
You got sent to an unknown place. "Eryn, wake up! Where are we!?"
Accumulated 20 hours of playtime. "That sounds like it'll take forever."
Fought 200 battles. "I didn't realize I was so strong."
Fought 50 battles. "This is nothing!"
Boosted your weapon for the first time. "This is simply the first step."
You became Eryn's Fencer. "Nice to meet you, Fang."
Obtained every trophy. "Thank you... I love you."
You saw the normal ending. "Yeah... Take care."
Pulled every sword from the Vile God and Goddess. "It took a long time but we're finally finished!"
Defeated 10,000 enemies. "There's no way I can stop!"
Performed 250 Hits. "I'll...cut you...to shreds!"
Lola joined the party. "Despite my appearance, I'm actually a fairy."
Reached level 99 with a character. "My coolness is about to reach godly levels."
Reached level 99 with every character. "They're calling themselves a hero's adventuring party..."
Boosted one of your weapons to its max. "With this, your combat strength has increased drastically!"
Cleared all 40 floors of Shukesoo's Tower. "Mwahahahaha!!"
Achieved a Quest Rank of S. "...I shall continue counting on you."
Accumulated 100 million G. "As usual, I smell the fragrant aroma of money coming from you today!"
Sealed the Vile God using Godly Revival. "Time to seal you away for good!"