Barista is someone who prepares and serves coffee drink in coffee house or the like, basically a coffee house bartender. Thus other than having the skill to prepare then to serve the coffee and a deep knowledge about the coffee, a good barista need to be good at interacting with the costumer.
Aoi Kouki is a barista who used to travel and hopping from one coffee house to another in Italia. One day someone from a big company took interest in his skill and invited him to work as a barista in a the company's new coffee house in Japan. He accepted the invitation and then his career as a barista in Japan started.