"Nasu: A Migratory Bird with Suitcase" is a sports drama anime that centers on Pepe Benengeli, a professional cyclist from Spain, as he competes in the Vuelta a España, one of the most prestigious cycling races in the world. The story unfolds over a single day of the race, capturing the physical and emotional challenges faced by Pepe and his fellow riders. Pepe, a domestique rider for his team, is tasked with supporting the team's star cyclist, but personal circumstances complicate his focus. His estranged wife, Carmen, has unexpectedly returned to their hometown, bringing with her a suitcase and a sense of unresolved tension. As Pepe navigates the grueling race, flashbacks reveal the complexities of his relationship with Carmen, their struggles, and the emotional weight he carries.

The narrative alternates between the intense, high-stakes environment of the race and Pepe's introspective moments, highlighting the interplay between his professional ambitions and personal life. The race itself is depicted with meticulous attention to detail, showcasing the strategies, teamwork, and physical endurance required in professional cycling. Pepe's interactions with his teammates, rivals, and the race dynamics provide a realistic portrayal of the sport. Meanwhile, the flashbacks to his life with Carmen add depth to his character, illustrating how his past influences his present decisions and mindset.

The main characters include Pepe, whose determination and vulnerability make him a compelling protagonist, and Carmen, whose presence looms large despite her limited screen time. The supporting cast, including Pepe's teammates and competitors, contribute to the authenticity of the cycling world. The anime balances the adrenaline of the race with the quieter, more reflective moments, creating a narrative that is both engaging and emotionally resonant. Through its focus on Pepe's journey, "Nasu: A Migratory Bird with Suitcase" explores themes of perseverance, sacrifice, and the intersection of personal and professional life.