The carrier, which is owned by Asiana, received permission from the DOT to service the United States on May 22.
The approval comes as Guam loses two low-cost carriers — EVA Air and HK Express.
In early May, HK Express issued a notice on its website that it will begin suspending flights to and from Guam starting June 26.
Growth in South Korea market
Korea, however, remains Guam's largest growing market and was able to overtake Japan arrivals in April.
According to Post files, South Korean arrivals made up 44 percent of Guam's entire visitor arrivals, compared to Japan's 41 percent last month.
Additionally, during the first four months of 2017, Japan arrivals showed an 11 percent decrease, while arrivals from South Korea increased 29 percent.
While tourism growth in Korea is good, the continued dips in Japanese arrivals continue to be "very concerning" and need to be mitigated, according to Monte Mesa, vice chairman of the Guam Visitors Bureau.