Here is the full list of all 42 Shoot Shoot My Waifu achievements.
Break a piece of cloth
Unlock Margaretta
Unlock Luceal
Unlock Liviatan
Unlock Satano
Unlock Secret sin
Get 5 stars on Sloth stage
Get 5 stars on Greed stage
Get 5 stars on Gluttony stage
Get 5 stars on Envy stage
Get 5 stars on Lust stage
Get 5 stars on Pride stage
Get 5 stars on Wrath stage
Get 5 stars on Secret sin
Clear all stages
Press the restart button after defeated on boss stage
Drink Matcha tea with Luceal
Swiming on Envy stage
Pick up the bride's bouquet from Wrath
Don't attack a flock of Debombs in any stage
Break all clothes without destroying ropes on Luceal's body
Kill 2 ducks with one attacking
Clear Wrath stage by using Exocist Skin
Don't attack the cat in Wrath stage
Purchase everything in Customize page
Lose the game while the boss has 3% HP or less
Leave love gauge fall to 0 in love scene
Clear any stage without destroying underwear
Reach checkpoint without killing any monster
Use skill Time Stop 10 times in the same stage
Insert Mr. Johnson into every characters
Exit love scene before the demon hits climax
Kill any boss by using ultimate skill
Clear all stages on hard difficulty without using ultimate and losing life
Stay in love scene at least 50 minutes
Stay in love scene less than 30 seconds
100,000 bullets were shot
Kill 30 mini bosses
Destroy 200 pieces of clothes
Destroy 1,000 bullets from monsters
Clear all stages twice
Collect 3 type of items