Mochi America, the first mochi character in the Hetalia universe, exists as a sentient, anthropomorphic mochi resembling the United States. He manifests as a flexible white blob capable of shape-shifting, spontaneously generating hands, legs, wings, mechanical arms, or miniature flags. His design features blue eyes and lines mimicking glasses, evoking his human counterpart. Among mochi, he ranks as the third hardest in texture.

His personality bursts with hyperactive, erratic energy. He communicates through fragmented English sentences, liberally peppering conversations with his signature phrase "It's okay, I'm an America" (or "American"). Compulsive tendencies define him, particularly his love for chocolate syrup and unhealthy foods; overfeeding or neglect triggers obesity. Despite chaotic antics, he holds no malice. He freely insults other mochi nations—labeling Mochi Italy a "pig" or Mochi Canada "hairy"—and has faced police encounters.

An absurd fixation casts lettuce as his paternal figure. Once, he devoured a lettuce leaf after calmly declaring it his father. Another time, he conspired with a sentient lettuce head for global destruction until Mochi Canada consumed it, plunging him into distress. Estonia discovered him and serves as his primary caretaker. Food easily wins his friendship, and he joins events like Christmas and Halloween alongside Estonia.

Adaptations feature him as a Kitayume website mascot in "Hetalia: The Beautiful World" and in brief anime segments. During eyecatches, he interacts with fellow mochi, questioning Mochi Italy’s nationality in English while flags appear. Alternate scenarios depict him targeted by Mochi Japan, who considers mochi edible due to their rice-cake nature.

His traits remain unchanged across official media, consistently functioning as a comedic, unpredictable presence in mochi spin-offs and anime adaptations.