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