Caproni is a famous Italian airplane designer who appears as a recurring figure in the dreams of the protagonist, Jiro Horikoshi. He is a fictionalized representation of the historical aeronautical engineer Giovanni Battista Caproni, and his primary function is to serve as an inspirational guide and a philosophical sounding board for Jiro throughout his life.

In terms of background, Caproni is an established and visionary figure in the world of aviation. His work and ideals are first introduced to the young Jiro through an imported aviation magazine, which plants the seed for Jiro's own aspirations. Caproni never meets Jiro in the real world; instead, he exists solely within the dreamscape, representing the embodiment of Jiro's professional ambition and creative drive.

Caproni possesses a vibrant and spirited personality. He is described as happy, fun, and humorous, with an infectious enthusiasm for flight. His demeanor is larger than life, yet he carries a deep and sincere wisdom about the nature of creative work and the moral complexities that come with it. He is often seen smiling and is remarkably benevolent, always encouraging Jiro to pursue his passion without being naive about the potential consequences. He affectionately refers to Jiro as the boy from Japan rather than using his name, which reinforces his role as an external, archetypal mentor figure.

Capronis core motivation is the creation of beautiful flying machines. For him, airplanes are like beautiful dreams, representing the pinnacle of human ingenuity and artistic expression. He believes in pursuing this dream passionately, even when faced with failure, as he demonstrates when one of his own designs crashes in a dream sequence. He is driven to inspire Jiro to also realize his dream, guiding him past the initial hurdle of his nearsightedness by revealing that he himself has never flown a plane.

The characters role in the story is multifaceted. He acts as the catalyst for Jiros journey, transforming a childhood fascination into a lifelong commitment to aeronautical engineering. He appears at several critical junctures in Jiros life, providing not only technical inspiration but also a framework for understanding the ethical dilemmas of his work. In one pivotal dream while Jiro is in Germany, Caproni poses the famous pyramid question, asking whether it is better to live in a world with or without pyramids, using it as a metaphor for technological progress. He asks Jiro if he would rather design planes even if they are used for war or not design them at all, which forces Jiro to confront the cursed nature of his dream head-on. Ultimately, Caproni serves as a narrative device that externalizes Jiros internal conflicts about creativity, morality, and loss.

The key relationship in the film is, of course, between Caproni and Jiro. It is a purely one-sided, non-physical relationship that exists entirely in Jiros subconscious. Caproni is the master to Jiros apprentice, a wise elder who validates Jiros struggles and elevates them to a universal level. While Jiro has other meaningful bonds, such as with his wife Naoko, Capronis role is unique as he represents the world of dreams and professional dedication, in contrast to Naokos reality and love. Their final encounter occurs in a dreamlike field of destroyed war planes after the conflict has ended, where Caproni absolves Jiro, telling him that even though his designs were used for destruction, his dream was nonetheless realized and beautiful.

Regarding development, Caproni himself remains a static character, a fixed ideal without an arc of his own. However, his function and the tone of his conversations evolve alongside Jiro. In Jiros childhood, Caproni is a purely inspirational figure who opens up the possibilities of flight. As Jiro matures and the shadows of war grow longer, Capronis guidance becomes more philosophical and somber, directly addressing the moral weight of creation. By the end of the film, his role shifts to that of a consoler, helping Jiro find peace with the legacy of his life's work.

Notable abilities of Caproni are tied to the surreal logic of the dream world. He has the ability to walk on and fly alongside his aircraft in mid-air, a recurrent visual motif that underscores his complete mastery and harmony with his creations. His primary ability, however, is not physical but intellectual and emotional. He possesses a profound capacity for mentorship, able to articulate complex ideas about ambition, failure, and morality through simple metaphors like pyramids and dreams. He can cross the boundaries of time, space, and death to appear to Jiro, offering perspective and a glass of very excellent wine at the very end of Jiros journey.