Espers are powerful, primordial beings that live in the Esper realm in Final Fantasy Airborne Brigade. The players and their brigade are tasked with battling them to earn their respect and ask for their help in restoring light to the remaining guardian crystal. Espers are both similar and different to weapons and abilities; they're equipped the same way and can be optimized by the system (separately from weapons and abilities), and they can be evolved to boost limits and enhanced to become stronger, but there the similarities end.