Here is the full list of all 69 DEEP SPACE WAIFU achievements. It takes around 1-2 hours to unlock all of the achievements on Windows.
Beat REMI with one hand
Play one hand mode with REMI
REMI naked
Beat the PLAGUE boss
Beat MITSUMI with one hand
Play one hand mode with MITSUMI
Beat MOKOTO with one hand
Play one hand mode with MOKOTO
Beat ARISA with one hand
Play one hand mode with ARISA
Beat MISAKO with one hand
Play one hand mode with MISAKO
Beat NIKITA with one hand
Play one hand mode with NIKITA
MITSUMI naked
ARISA naked
MISAKO naked
NIKITA naked
Beat YUMI with one hand
Play one hand mode with YUMI
60% of clothes off REMI
30% of clothes off REMI
Play with all the girls
Unlock REMI TACHIBANA
Beat NEKOTINE with one hand
Beat the ARMORY boss
NEKOTINE naked
Play one hand mode with NEKOTINE
Beat SARAH with one hand
Play one hand mode with SARAH
60% of clothes off ARISA
30% of clothes off ARISA
60% of clothes off MISAKO
30% of clothes off MISAKO
60% of clothes off NEKOTINE
30% of clothes off NEKOTINE
Unlock NEKOTINE
60% of clothes off NIKITA
30% of clothes off NIKITA
YUMI naked
60% of clothes off YUMI
30% of clothes off YUMI
Unlock ARISA MIKEA
Gain 18 stars
MOKOTO naked
60% of clothes off MOKOTO
30% of clothes off MOKOTO
Unlock NIKITA DORMER
Unlock MISAKO AOYAMA
Unlock YUMI MATSUDA
Beat the VULCAN boss
60% of clothes off MITSUMI
30% of clothes off MITSUMI
SARAH naked
Beat TOMOKO with one hand
Play one hand mode with TOMOKO
Unlock one hand mode
60% of clothes off SARAH
30% of clothes off SARAH
TOMOKO naked
Unlock MITSUMI KATAGIRI
Date with a girl
Beat the SAMURAI boss
Gain 5 stars in one girl
60% of clothes off TOMOKO
30% of clothes off TOMOKO
Explode your first piece of clothes
Play the dating app
See the credits