Invincible Kungfu Healer - Chapter 1004 - The Ninth Spirit Mountain

Princess Leah wrote a suicide note ahead of her wedding.

The empire has turned into the land of the undead due to a spell gone wrong. God summoned heroes from countless worlds to purify the empire and plant new hope. Lee Shin Woo, an ordinary earthling, was also summoned. As an undead, that is.

A tale about the former leader of a special organization served under royalty, now leaving his past life behind and unintentionally getting involved with the martial world.

- Description from Novelupdates

16 years old-- most boys would be falling in love, as their hormones all rise to unprecedented levels. Most boys at Riley's age would have dreams; dreams that will slowly grow into passion. Riley, however, at age 16... killed the world's number 1 superhero.