"Words Bubble Up Like Soda Pop" is a coming-of-age anime film that intertwines the lives of two teenagers, each grappling with their own insecurities. The story centers on Kouichi "Cherry" Sakura, a shy and introverted boy who expresses himself through haiku poetry, and Smile, a bubbly and energetic girl who hides her braces behind a face mask and finds solace in creating online content. Both characters meet at a shopping mall, where they are drawn into a summer adventure that challenges their fears and helps them grow.

Cherry struggles with social anxiety, often retreating into his poetry to navigate the world. Smile, despite her outgoing online persona, is self-conscious about her appearance and avoids showing her smile in real life. Their paths cross when Cherry is tasked with delivering a lost item—a vinyl record belonging to an elderly man named Fujiyama, who is searching for a long-lost memory tied to the record. Smile, working at the mall's photo booth, joins Cherry in this quest, and together they embark on a journey to uncover the story behind the record.

As the two spend more time together, they begin to open up about their struggles. Cherry’s haiku becomes a medium for expressing his feelings, while Smile gradually gains confidence to reveal her true self. Their friendship deepens as they navigate the challenges of adolescence, including misunderstandings, moments of vulnerability, and the pressure to fit in. The narrative also explores themes of connection and memory through Fujiyama’s story, which serves as a poignant backdrop to the teenagers’ personal growth.

The film’s setting, a vibrant and nostalgic summer landscape, complements the emotional tone of the story. The mall, with its lively atmosphere, becomes a central hub where the characters’ lives intersect, and the search for Fujiyama’s past adds a layer of mystery and sentimentality. Through their shared experiences, Cherry and Smile learn to embrace their imperfections and find strength in their unique identities, culminating in a heartfelt resolution that underscores the importance of self-acceptance and human connection.