Before the development of the VF-4 Lightning III, Stonewell/Bellcom built the VF-X-4 trial-production variable fighter as a prototype for the VF-4. The VF-X-3 was also built around the same time. Development started in 2005 and eventually test flights were conducted in which some VF-X-4 flights were flown by Space War I veteran Hikaru Ichijyo.
The trial-produced VF-X-4 featured most of the key design features that would be included in the final VF-4 Lightning III design, but was initially built using 35% VF-1 Valkyrie parts (notably, the nose and forward fuselage of the VF-1 fighter). Hikaru Ichijo had a scale model of the VF-X-4 in his house in Macross City on Earth.