In the end, Fan Ren was at his wit's end and began calling out the name "Sin."

Although that killer was ruthless, he was still a person, which prevented Fan Ren from feeling like he had been thrown into another world alone.

Moreover, that guy had sharp senses. If Fan Ren called him, he would probably come out to kill him soon... and then he could beg for mercy.

Fan Ren thought it through, but the reality was completely contrary to his expectations. From cautious probing at the start to shouting at the top of his lungs on campus, there was no response at all.