Mirror Game - Volume 1 - manga

A Fatal Hypnosis
"In 15 days, you will commit suicide."

K gains the world's attention by using Youtube to successfully hypnotize people twice. Later, his show is broadcast live in 120 countries as he attempts to hypnotize viewers. In this show, K casts a hypnotic spell that everyone who watches this show will commit suicide 15 days later, sending the entire world into a panic. K bids his audience goodbye and disappears.
In the hope of finding K, Cha Jihyeon, a member of the Seoul Criminal Investigation Department, has only one lead: Seo Jinwoo, a young man with amnesia.