Please Call Me Ghost Messenger is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

After the eternal night, terror resurges! Supernatural ghosts and monsters descend upon the modern city! All common knowledge and rules are overturned! Blood rains down beneath the calm campus, tombstones crack open in the outskirts’ cemetery, and dilapidated apartments are haunted by numerous apparitions… In this dark and desperate environment, there stands a midnight-revealing post office, and a young boy dressed in black navigates through mysterious and terrifying places. The young boy in black becomes the forbidden legend in people’s mouths, “He is the Great Lord of the Underworld!”