"Sayonara, Tyranno" is a short anime series that adapts the story from a picture book by author and illustrator Tatsuya Miyanishi. The narrative centers on a young dinosaur named Tyranno, who is feared and ostracized by other dinosaurs due to his size and strength. Despite his intimidating appearance, Tyranno is gentle and longs for companionship. One day, he encounters a small dinosaur named Hoshi, who is unafraid of him and seeks his protection. The two form an unlikely bond, with Tyranno becoming a guardian figure to Hoshi.

As the story progresses, Tyranno and Hoshi face challenges that test their relationship. The world they inhabit is harsh, with natural disasters and predatory threats constantly looming. Tyranno's protective instincts are put to the test as he strives to keep Hoshi safe, while Hoshi's curiosity and adventurous spirit often lead them into danger. The series explores themes of friendship, trust, and the struggle to overcome prejudice, as Tyranno's kind nature gradually earns him acceptance from others.

The plot takes a poignant turn when a catastrophic event threatens the survival of all dinosaurs. Tyranno must make a difficult decision to ensure Hoshi's safety, leading to a bittersweet conclusion that underscores the depth of their bond. The story is emotionally resonant, blending moments of warmth and humor with a sense of inevitable loss, reflecting the transient nature of life.

The main characters, Tyranno and Hoshi, are central to the narrative. Tyranno's character arc focuses on his journey from being an outcast to finding purpose and connection through his relationship with Hoshi. Hoshi, on the other hand, represents innocence and resilience, serving as a catalyst for Tyranno's growth. The series is concise, with a runtime that allows for a focused exploration of its themes and characters, making it a compact yet impactful viewing experience.