Based on a shounen gag manga by Masuda Kousuke serialised in Monthly Shounen Jump.

Uro Yamada works as part of the "Hero Retirement and Return to Everyday Life Assistance Agency," which takes heroes from another world back to Earth and helps them reintegrate into everyday life.

The young Kimball Kinnison is leaving home for a wider education when a Galactic Patrol ship crashes on his family's land and the dying pilot gives him a mysterious Lens. Half-sentient, the Lens now implanted in his hand becomes the focus of changes in Kim's life including his father's death, a space battle, and an encounter with Galactic Patrol nursing officer Chris. Impelled by the Lens, he discovers a new world of experiences opening before him and he risks his life to save Chris and the Universe. (Source: AniDB)

Hiroshi Shiba is an outstanding car racer whose father is assassinated upon the discovery of the Bronze Bell from an ancient civilization. This Bronze Bell is coveted by Queen Himika who comes from that ancient era; the Yamatai Kingdom, and whose ambitions are to seize the Bell and dominate earth. Hiroshi is left with a few items from his father which would enable him to morph into a full sized mecha warrior, the Steel Jeeg. With these abilities and the help of his father's brain implanted in a computer and his assistance Miwa "Micchi" Uzuki, they set out to neutralize Himika's plans of world dominion.