When I Gained the Power of Invisibility, I Wanted to Start Enjoying Everything

A young man hears his mother and younger sister arguing about him while he's in his room. His sister has hated him since childhood, and their conversation makes her contempt clear. Frustrated, he returns to his room and receives a mysterious phone call from an unknown number, which he initially dismisses as a scam. After hanging up, he realizes he hasn't eaten and reluctantly leaves his room to face his sister. However, he quickly discovers something strange: his sister appears unable to see him. Was that mysterious phone call real, or has something supernatural happened?