Now I understand. I think this is what happened yuki loved hojo but he was afraid hojo would hate him if he founds out his feelings so he hide his feelings and started collecting photos and just stayed as his friend but his sister didn't like how yuki is close to hojo so she sent that girl after yuki to cover her plan. She's is the one who sent hojo those threats and photos to make it look like that girl did it. Yuki knew her sister was the one who sent those photos because they were his photos but she refused to stop and she framed yuki as hojo's stalker so hojo would hate him and yuki tried to convince hojo but he fell down but I don't know if yuki or his sister pushed hojo. Well, this is what I think ?