Believing in "sexual pleasure makes the world better", Ona Ittetsu, encountered an enormous earthquake while masturbating.
He died before he could finish. However, he entered some unknown space while dying. All of the sudden a goddess appears to grant him the mission to “save the world with sexual pleasure”. He becomes TENGAMAN.
TENGAMAN's first enemy was a guy, Fujimoto, who doesn't erect at all. Eventually TENGAMAN made this dreadful enemy to cum and told him the real meaning of pleasure. But peace just doens’t last.