You and Setsurou have been dating for a while now, although the only reasons behind it is because he's a yandere, he just adores you! The only problem dating a yandere is that he'll kill anyone who "gets too close to you" and/or if they're a potential threat to your relationship, but you've gotten used to it... Sort of

one day you were by yourself in a secluded area of the school that you'd always go to be alone, when you feel a pair of arms wrap around you from behind, it was Setsurou