Ultraman: Ultimate Force Zero

In the future, the sun mutates, and living things exposed to its rays have a chance of growing gigantic. But humans cannot withstand the power of gigantification, and die as a result. This once dealt a devastating blow to human civilization. Fortunately, a mysterious being on humanity's side, calling himself Ultraman King, taught them how to build the Plasma Spark Tower. Thanks to it, some humans can grow gigantic, transforming into giants, monsters, and aliens.