Following their shock prevail upon Germany, Japan were baffled by a tight guarded unit, before Fuller hit with Costa Rica's previously shot on track at the competition.
The outcome leaves the two groups on three focuses after two games, with Spain - who actually top the gathering on objective contrast - confronting Germany later on Sunday (19:00 GMT).
Triumph for Spain will everything except ensure their movement to the last 16.
How Japan 0-1 Costa Rica unfurled
In the wake of beating Germany in their opener, many anticipated that Japan should represent a Costa Rica side faltering from a 7-0 whipping by Spain.
In any case, Japan manager Hajime Moriyasu picked turn over coherence, rolling out five improvements, and that brought about a repressed exhibition and a scoreline that completely exposed the gathering.
It was a striking triumph for Costa Rica, who had neglected to lay a glove on the Japan safeguard before Fuller's diverted shot from the edge of the crate got away from goalkeeper Shuichi Gonda's grip a little ways from time.
After a first half without goalmouth activity in the singing intensity at Ahmad Container Ali Arena, Japan overwhelmed for enormous spells. Nonetheless, they attempted to make obvious possibilities until the 88th moment, when Daichi Kamada couldn't turn the ball home after a driving Kaoru Mitoma run.
Having accomplished reclamation following their embarrassment because of Spain, the Costa Rica players celebrated genuinely at full-time as Japan were passed on to lament a disheartening showcase that neglected to back up their heroics against Germany.