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