Here is the full list of all 15 Re:Touring achievements.
Get the sakura flavored drink in level 22.
Solve level 15 with only 3 rules.
Solve level 21 with only 4 rules.
Solve level 16 with only 4 rules.
Solve level 25 with only 5 rules.
Buy all drinks from a vending machine.
Listen to one of the record players in the game.
Try to open 15 locked doors throughout the game.
Complete the game.
Complete the game without having a puzzle solved by the hint system.
Complete the game without using the hint system at all.
Solve two puzzles in a room in the wrong order.
Successfully create your first endless loop.
Sit down to rest on one of the chairs in the game.
Jump into water.