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.
Accumulated 20 hours of playtime. "That sounds like it'll take forever."
Apollonius joined the party. "I'll become your overseer."
Reached level 10 with one of your fairies. "There's still much we don't know about fairies."
Eryn powered up. "If I decide to get serious, I'm capable of all kinds of things."
Fought 200 battles. "I didn't realize I was so strong."
You got sent to an unknown place. "Eryn, wake up! Where are we!?"
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 Tiara's ending. "You have changed everything for me."
You saw Eryn's ending. "I'm hungry, too!"
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!"
Maxed your tension 300 times. "I'm fired up!"
Performed 250 Hits. "I'll...cut you...to shreds!"
Lola joined the party. "Despite my appearance, I'm actually a fairy."
Performed 100 Avalanche Attacks. "We're invincible!"
Performed 100 Air Combos. "There!"
Dealt 100,000 damage. "With this one blow!"
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!"
Fought 500 battles. "Fwoooooosh!"