Here is the full list of all 52 Jerez's Arena achievements.
Win Claudia's first battle
Reach any Ending
Bad End
Accumulate 100000 G worth of wealth
Win Ellin's third battle
"Stamina" reached 200!
"Dexterity" reached 200!
"Strength" reached 200!
"Willpower" reached 200!
Ellin completed her 30th Training
"Kinkiness" reached 200!
"Agility" reached 200!
"Lewdness" reached 200!
"Seduction" reached 200!
"Technique" reached 200!
"Obedience" reached 200!
Fed the birds with Claudia
Win Claudia's third battle
Win Ellin's second battle
Completed Claudia's Oiran Request
Punished Ellin for stealing
Ellin completed her 30th Conditioning
Win Claudia's second battle
Stopped the Noble from bullying Claudia
Claudia completed her 30th Training
Ellin completed her first Training
Completed the Undercover Mansion Mission
Ellin completed her first Mercenary Commission
Ellin completed her first Prostitution Quest
Ellin completed her first "training" Conditioning
Ellin joined the team!
Claudia completed her first Mercenary Commission
Completed the Bandit Mission
Claudia completed her first Training
Claudia completed her first Prostitution Quest
Claudia completed her first Conditioning
Win Ellin's first battle
Claudia completed her 30th Conditioning
Claudia completed her 20th Prostitution Quest
Claudia completed her 20th Mercenary Commission
Ellin completed her 20th Prostitution Quest
Ellin completed her 20th Mercenary Commission
Saved Ellin at the Tavern
Watched Ellin dance
True End
Claudia End
Ellin End
Earned All Achievements
Lose All Battles
Defeated Glenn at the height of his power in Conqueror Mode.
Defeated Isekai Adventurer Lica in Conqueror Mode.
Cleared Conqueror Mode.