Here is the full list of all 50 MonGirl Expedition achievements.
Meet Mona
Max out Mona's affection
Meet Elly
Max out Elly's affection
Meet Mariam
Max out Mariam's affection
Meet Belle
Max out Belle's affection
Meet Naka
Max out Naka's affection
Meet Rena
Max out Rena's affection
Beat the giant slime
Beat Facesmasha
Beat the slavemaster
Beat the sand genie
Beat the sacred guardian
Beat the dark lady
Ascend with Leopold's help
Beat the doppler
Beat Shrike
Beat Morghul the unclean
Beat Leopold
Beat Zathol
Dig up a treasure
Dig up all treasures
Win in arm wrestling
Win in blackjack
Catch the elusive rabbit
Make a diversion
Get an illusion for any girl
Get all illusions from Meggie
Get Elly's good ending
Get Elly's bad ending
Get Naka's good ending
Get Naka's bad ending
Get Mona's good ending
Get Mona's bad ending
Get Belle's good ending
Get Belle's bad ending
Get Rena's good ending
Get Rena's bad ending
Get Mariam's good ending
Get Mariam's bad ending
Beat magical armor
Beat Fang
Beat Sand guardian
Meet Hanako
Max out Hanako's affection
Beat Huge bear