In the "Amber Land", a continent where there is no light all day long, there is a sacred profession - the messenger bee. In this dangerous place where artificial sun cannot shine and darkness spreads, the messenger bees are willing to deliver important "letters" for the people at the risk of their lives. Gao Xiu (voiced by Jun Fukuyama) is an excellent messenger bee. The "letter" he has to deliver today is a boy named Ragu (voiced by Miyuki Sawashiro). Ragu's mother was forcibly taken away by a group of strangers one day. Ragu's mother sent him as a letter to her aunt's house in a small town outside the sea. During the delivery, Ragu was attracted by Gao Xiu's strong and gentle heart. Because of his admiration for Gao Xiu, Ragu decided to become an excellent messenger bee. At the age of 12, he passed the exam to become a messenger bee, but unexpectedly discovered that Gao Xiu was no longer a messenger bee, and had lost his "heart" and his whereabouts were unknown. Ragu embarked on the road of a messenger bee, delivering letters of people's "heart" and "hope". He wanted to find Gao Xiu... Adapted from Hiroyuki Asada's fantasy-style boy manga "Messenger Bee".