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