Here is the full list of all 44 Sonicomi achievements.
Beat the game on Hard difficulty.
Complete 50 photo shoots.
Get a combo score of 200.
Get an SS ranking on a photo shoot.
Get Ending 08.
Beat the game on Easy difficulty.
Beat the bonus stage.
Go on a first date with Sonico.
Get a combo score of 100.
Get Ending 01.
Get Ending 02.
Get Ending 03.
Get Ending 04.
Get Ending 05.
Get Ending 06.
Get Ending 07.
Get Ending 09.
Get Ending 10.
Get Ending 11.
Get Ending 12.
Get Ending 13.
Get Ending 14.
Get Ending 15
Get Extra Ending 01.
Get Extra Ending 02.
Get the True Ending.
Beat the game on Normal difficulty.
Complete 10 photo shoots.
Complete 100 photo shoots.
Photograph a sub-target.
Get a bad ending.
Go on a second date with Sonico.
Unlock all clothing items.
Unlock all accessories.
Unlock all hairstyles.
Unlock all backgrounds.
Complete all Client Requests.
Photograph 100 sub-targets.
Get all bad endings.
Get all good endings.
Buy everything in the Ouka Shop.
Reach maximum affection with Sonico.
Take no photos during the tutorial.
Unlock all outfit parts.