Here is the full list of all 37 The Caligula Effect: Overdose achievements.
Acquire all achievements.
Solve the mystery of the 21-class leader.
Complete the main story with both the male and female protagonist.
Complete all Go-Home Club members' Character Episodes.
Complete μ's Character Arc.
Complete Thorn's Character Arc.
Complete Aria's Character Arc.
Exterminate the Go-Home Club.
Complete all Ostinato Musicians' Character Arcs.
Solve all Enigmas.
Complete μ's Remnant Episodes.
Clear a melee battle.
Raise the protagonist's level to higher than 50.
Complete Wicked's Character Arc.
Complete Shadow Knife's Character Arc.
Complete a person's Character Episode.
Banish Eiji from the Go-Home Club.
Clear the Shogo and Izuru battle.
Complete Ike-P's Character Arc.
Clear the Kotono and Eiji battle.
Complete Mirei's Character Arc.
Accumulate over 100 friends with ★ Affinity.
Complete Kuchinashi's Character Arc.
Collect over 300 Stigmas.
Clear the Suzuna and Naruko battle.
Complete Shonen-Doll's Character Arc.
Clear the Mifue and Ayana battle.
Complete Stork's Character Arc.
Accumulate over 100 friends.
Begin activities as part of the Ostinato Musicians.
Complete Sweet-P's Character Arc.
Send group WIRE messages over 10 times.
View your field WIRE over 10 times.
Complete Kagi-P's Character Arc.
Begin activities as part of the Go-Home Club.
Experience your first battle.
Answer μ's call.