Run Run Killer!

What would you do if all you knew was ripped into shreds little by little..
In her second year of highschool Yachi went out to buy groceries for the apartment while her mom was out at work. She runs into a former friend Bokuto koutarou.. Little does she know a twist of a knife and fate are going to change their lives.
Shimizu rushes to Yachi and Koutarous aid..
but who was truly behind their grief?
" Keiji... Dont!" ...