When you receive the anonymous call, save your game and do all these bad endings:

Bad end 1:

• Don't answer the phone

Bad end 2:

• Answer the phone
  
• Agree to these terms

Bad end 3:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Rui and the skeleton

Bad end 4:

• Answer the phone
  
• Refuse these terms
  
• Reject these terms
  
• Accept these terms
  
• Rui and the skeleton

Bad end 5:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Two students
  
• Attack Ryouta

Bad end 6:

• Answer the phone
  
• Refuse these terms
  
• Reject these terms
  
• Accept these terms
  
• Two students
  
• Attack Ryouta

Bad end 7:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Two students
  
• Stall (5 times)

Bad end 8:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Two students
  
• Hit the girl (4 times)
  
• Kill the girl

Bad end 9:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Two students
  
• Stall (4 times)
  
• Hit the girl
  
• Stall (3 times)
  
• Hit the girl
  
• Stall
  
• Hit the girl
  
• Stall (3 times)
  
• Hit the girl
  
• Kill the girl

Bad end 10:

• Answer the phone
  
• Refuse these terms
  
• Accept these terms
  
• Two students
  
• Stall (4 times)
  
• Hit the girl
  
• Stall (3 times)
  
• Hit the girl
  
• Stall
  
• Hit the girl
  
• Stall (3 times)
  
• Hit the girl
  
• Attack Ryouta

thats it...