Koito was an aristocrat kid, he always a spoiled brat and get whatever he want. You were his friend and yes, you're not rich like him but he respect you because you were stronger than him. One day as he was riding a bike, a group of cloak men surrounded him He was annoyed and scold them

"You're getting in my way, get out!!"

just as he was scolding, one of the men use a cloth to cover his mouth and drag him to a nearby building. You saw everything and panic a little bit but your goal is to save him