In Episode 12, the story focuses on the preparation and performance of the New Year's show. Yukine admires Mahiru's ability to secure JELEE's spot in the show through solid statistics but questions her motives. Mahiru reveals that she wants to help Kano sing again as thanks for the support she herself received from Kano. Kano feels lost without Yukine and Mahiru's support and is nervous about performing in front of a live audience in the park. Her friends Kiui and Mei stand by her side and help ease her fears.

During the performance following the SunDolls, Kano is overwhelmed by self-doubt, but Mero's unexpected encouragement and the park's resemblance to her dreamlike "Shibuya Aquarium" help her find her voice. Mahiru supports her from above the stage, further strengthening Kano. With the backing of former rivals and friends, Kano delivers an impressive performance that lights up the stage. Kiui invests JELEE's earnings into a 3D model of a JELEE girl.

After the performance, Mahiru and Kano try to reunite but end up on opposite escalators. Eventually, they embrace and apologize for past hurts. As the credits roll, Kiui and Mei join them. Kano, unable to find her mother right away, is acknowledged by Yukine in the credits, bringing her emotional relief.

The finale highlights the personal growth of all the characters: Kano, Kiui, Mahiru, and Mei graduate from school. Kiui continues to nurture her relationship with Koharu, Mei gains her own superfan, and Yukine praises her daughter's growth. Kano reconciles with Mero, and they evolve from colleagues to friends.

The members of JELEE celebrate their journey by repainting Mahiru's old mural together and capturing the moment with their phones. The episode ends with the once-aimless "jellyfish" now vibrant and independent. This symbolizes their growth and unity, bringing the series to a touching and satisfying conclusion.