Go Ryokou wa Anoyo Made? Shinigami wa Ueno ni Iru

Kaede, a young man struggling to find a job after graduation, nearly drowns in a river while trying to save an elementary school student. While unconscious, he dreams of meeting a man named who calls himself the "Grim Reaper." When he regains consciousness, the man's business card is left in his possession…!?

(Soruce: Shueisha, translated)