First-year high school student Uka Ishimori wants a fresh start. In middle school, Uka was given the nickname "Rocky" by her peers, being misunderstood as having no emotions when she was actually shy and introverted. As a result, Uka was relentlessly bullied and experienced a lonely, isolated school life. Now, Uka is determined to change.

During the first week of school, Uka accidentally gets drenched in lemon soda by her classmate Kai Miura—whose cool personality is the complete opposite of hers. After the incident, Uka is surprised when Kai performs small acts of kindness for her, encouraging her to gradually break out of her shell. Like a lemon soda, bubbly and exciting feelings are beginning to stir.