Aura Battler Dunbine (1983)

The setting is Byston Well, a fantasy world resembling Medieval Europe and including fantasy animals, such as unicorns. The local population uses insect-like fighting suits called Aura Battlers in the various wars between rival factions. The fighting suits are powered by a powerful energy called "aura" or "life energy". Certain people have enough energy to act as a power-supply to the suits. Motocross rider Sho Zama is teleported to this world as a new recruit because he has the potential for producing unlimited energy. He has to get used to near constant warfare, alongside a number of allies. Sho twice finds ways to revisit Earth, but his estranged family fails to recognize him. He realizes that he has no option to return to his former life.