The Su-37 Super Flanker-R is a specialized variant of the Su-37 Super Flanker aircraft fielded by the UPEO, modified exclusively for the organization's flight prodigy, Rena Hirose. The -R model possesses several hardware differences with the original Flanker, such as the Opto-Neuron-Synapse-Interface (ONSI) neural link system and a reinforced airframe adapted for Rena's flight capabilities.
The Su-37R was created at some point after Rena Hirose joined the UPEO. It is the only aircraft known to be used by her during the Intercorporate War, with the exception of the X-49 Night Raven. After Rena joins Ouroboros, she replaces her Su-37 with the X-49, as such, the custom Flanker doesn't make a single appereance afterwards.