Oniisan

This character whose name and age are unknown is a man who always covers his face with a mask, and is notable for his silver-colored hair. He first appears as Sachi's "stalker"—he took a lot of picture of her and put them on a wall at his home. After saving Sachi from committing suicide, he decided to give Sachi a chance to "taste happiness" while doubting whether what he does—kidnapping her—is the right thing to do.

At childhood he was named "Haru". He decided to reveal his name to Sachi in volume 7, because he is convinced that Sachi won't die before him.