Here you can find links to all of the walkthroughs for Collar x Malice.
When you start Collar x Malice, Aiji’s route will be locked until you clear the stories of the four other bachelors (sorry if you were itching to date the group’s otousan first). On top of this, you won’t be able to choose Shiraishi’s route until at least your second playthrough—however, I strongly recommend you save the enigmatic profiler until your 4th playthrough because his route is pretty spoiler-heavy.
My recommended route order would be:
Mineo or Takeru → Kei → Shiraishi → Aiji
Everyone apart from Aiji shares a common prologue, and you can choose to only play this twice to get to the save point where the game branches into the individual routes—if you don’t feel like playing the same chapter 4 times.
Banner image: Collar x Malice | IDEA FACTORY / DESIGN FACTORY