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
Beat NEKOTINE with one hand
Play one hand mode with NEKOTINE
Beat the PLAGUE boss
REMI naked
60% of clothes off REMI
30% of clothes off REMI
NEKOTINE naked
60% of clothes off NEKOTINE
30% of clothes off NEKOTINE
Beat ARISA with one hand
Play one hand mode with ARISA
Unlock REMI TACHIBANA
ARISA naked
60% of clothes off ARISA
30% of clothes off ARISA
Beat MISAKO with one hand
Play one hand mode with MISAKO
Beat the ARMORY boss
MISAKO naked
60% of clothes off MISAKO
30% of clothes off MISAKO
Beat MITSUMI with one hand
Play one hand mode with MITSUMI
Unlock NEKOTINE
Play with all the girls
MITSUMI naked
60% of clothes off MITSUMI
30% of clothes off MITSUMI
Beat TOMOKO with one hand
Beat NIKITA with one hand
Play one hand mode with NIKITA
NIKITA naked
60% of clothes off NIKITA
30% of clothes off NIKITA
Beat YUMI with one hand
Play one hand mode with YUMI
Unlock ARISA MIKEA
Gain 18 stars
YUMI naked
60% of clothes off YUMI
30% of clothes off YUMI
Beat MOKOTO with one hand
Play one hand mode with MOKOTO
Unlock MISAKO AOYAMA
Unlock NIKITA DORMER
MOKOTO naked
60% of clothes off MOKOTO
30% of clothes off MOKOTO
Beat SARAH with one hand
Play one hand mode with SARAH
Unlock YUMI MATSUDA
Beat the VULCAN boss
SARAH naked
60% of clothes off SARAH
30% of clothes off SARAH
Play one hand mode with TOMOKO
Unlock one hand mode
TOMOKO naked
See the credits
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