Following her grandfather's passing, Mikura takes over their island courier service, using her seaplane and trusty cat, Endeavor, to embrace a free-spirited life. Intrigued by a legendary shifting island, she embarks on a quest to locate it. After a relentless search, Mikura catches a fleeting glimpse of the elusive land from above, sparking her unwavering resolve to rediscover it at any cost.