He had always felt something was off about Yashiro Sensei especially since his face looked weirdly similar to face of his mother's killer which all he got was a glimpses of his face as he had watched him get caught by the police in 2006. It even irked him more when he had told his sensei about the bruises he saw on Kayo and smiled and said he knew since last May that something was up. He wasn't about to put his guard down for anyone he thought was susprious in killing Kayo, Hiromi, and aya. And most of all he never ever wanted to look at his mother bleeding staved in the side again. He, Satoru Fujinuma had to save the lives of all these people. He wouldn't slip up and get them killed (and possibly himself this time). He couldn't fail this time.