Kouya no Kotobuki Hikoutai Gaiden: Oozora no Harukaze Hikoutai

Kouya no Kotobuki Hikoutai Gaiden: Oozora no Harukaze Hikoutai is a web-based ONA series released in 2019 as a companion project to the main Kouya no Kotobuki Hikoutai anime series. Produced by studio GEMBA, these shorts were designed to expand the world-building of the franchise, focusing on the everyday lives and minor missions of the characters within the aviation-themed setting. The shorts utilize the same digital cel-shading techniques as the primary series, maintaining visual consistency while shifting the narrative tone toward lighthearted, episodic storytelling.

The production was spearheaded by director Tsutomu Mizushima, who sought to leverage the 3D animation pipeline to showcase intricate aerial dogfights and character-driven interactions. By providing supplemental narratives through this ONA format, the production team aimed to deepen the audience's investment in the secondary cast of the Kotobuki Squadron. While the broader franchise received varied responses regarding its reliance on 3D computer graphics for character models, this spin-off was received by fans as a thoughtful addition that successfully captured the atmosphere of the series' established dieselpunk world.