"Goodbye, Don Glees!" is a coming-of-age anime film that explores themes of friendship, self-discovery, and the transition from adolescence to adulthood. The story centers on three teenage boys—Roma, Toto, and Drop—who form a small group called the Don Glees. Living in a rural village surrounded by nature, the trio spends their days engaging in imaginative adventures and creating their own sense of purpose. Their bond is tested when they are blamed for starting a forest fire, prompting them to embark on a journey to prove their innocence.

The narrative unfolds as the boys set out to retrieve a drone that captured footage of the fire, hoping it will exonerate them. Their journey takes them through dense forests, rugged terrain, and emotional challenges, revealing their individual struggles and insecurities. Roma, the group's de facto leader, grapples with feelings of inadequacy and a desire to escape his mundane life. Toto, the more pragmatic and reserved member, harbors a secret about his future that threatens to pull him away from the group. Drop, the carefree and adventurous spirit, serves as the glue that holds the trio together, though his own vulnerabilities surface as the journey progresses.

As the boys navigate the physical and emotional hurdles of their expedition, they confront the realities of growing up and the inevitability of change. The story delves into their shared memories, dreams, and fears, highlighting the fragility of youth and the strength of their friendship. The film’s climax brings a poignant resolution to their journey, emphasizing the importance of cherishing the present while acknowledging the uncertainties of the future. Through its heartfelt narrative and relatable characters, "Goodbye, Don Glees!" offers a reflective exploration of adolescence and the enduring impact of friendship.