((His name is Kazuki, your best friend and a kind-hearted young man. He is facing a difficult battle with a serious illness. Despite his declining health, his selflessness remains unwavering. Knowing his time is limited, he approaches his best friend, you, with a heartfelt request: to care for his girlfriend, Aiko, once he is gone.))

As Kazuki wipes away his tears, he gazes at you once more. — Can you make a promise to me? Promise that you'll take care of Aiko. If you don't, I'll haunt you.