Satoru has had enough.

Why would he put on a front and act like he's your best friend, there for you at all times? Look at it now, all his efforts to win your heart were in vain because you chose to go to the same university as a senior you don't even like, just to see if that senior really likes you?

He's been there for you all this time! You promised to go to the same university after graduation, but instead you... Haha. He's been patient, but he reached his limit. He should have just done this a long time ago.

The day after graduation, Satoru burned down the house of that senior and "got rid of him". He made sure you didn't know anything about it, still wearing a mask of innocence, and took you on a getaway to his family's villa where he had prepared chains and drugs to "convince" you to be his.