Episode 5 of "クラゲは夜に泳げない" ("Jellyfish Can't Swim in the Night") begins with JELEE's first music video unexpectedly going viral due to a mix-up where an early version of the song was uploaded. This version contains a background recording of Kano's sister talking in her sleep, leading to rumors that the video is cursed. Nonetheless, the response is overwhelmingly positive, boosting the group's online presence and follower count.

Inspired by the video's success, Yoru dreams of creating more elaborate artworks in future projects. However, her confidence is shaken by a critical comment about her art and the appearance of beautifully crafted fan art by a well-known online illustrator named Kuroppu. Yoru feels overshadowed and begins to question her own talent. She struggles with feelings of inadequacy within the group, which consists of experienced artists.

Noticing Yoru's distress, Kano visits her to offer support. During their conversation, Yoru expresses her fear of being ordinary compared to her talented peers. Kano reassures her that her art, which played a crucial role in the group's formation, is uniquely valuable. Kano's encouragement eases Yoru's self-doubt slightly, but the praise Kuroppu receives online continues to unsettle her.

A live Q&A session amplifies Yoru's insecurity when a viewer suggests using Kuroppu's art instead of hers. Although Kano defends Yoru's contributions, Yoru later seeks validation for the quality of her art compared to Kuroppu's, which Kano sidesteps by focusing on emotional support. Eventually, they visit an aquarium, where Kano praises Yoru's complex personality and promises to support her dreams.

Later, after encountering another impressive artwork and revisiting the critical remark that triggered her insecurity, Yoru resolves to improve her skills. She begins an intensive study of jellyfish and dedicates herself entirely to her art. This renewed dedication results in a piece that reignites Kano's admiration, validating Yoru's efforts and bringing her emotional relief.

The group releases a new music video, marking a fresh start after the "cursed" incident. Their successful collaboration and celebrating the New Year together strengthen the bond between Yoru and Kano. Yoru's growing confidence in her artistic identity and her appreciation for Kano's influence on her life culminate in a tender moment where Kano kisses Yoru, deepening their emotional and possibly romantic connection.

The episode ends with the girls enjoying the success of their new video, leaving viewers to reflect on the evolving dynamics within JELEE—particularly between Yoru and Kano—as they navigate friendship, collaboration, and budding feelings.