Ultraman: What do you mean by saying L77 is about to explode?

Reincarnated as Leo and Astra's younger brother, Prince Koul of Nebula L77 dreams of transforming into a 50-meter-tall giant of light and becoming a cosmic police officer. However, during his coming-of-age ceremony, while his brothers transform into giants of light, he's stuck at 1.8 meters! Not only can he not grow to giant size, but why, as a pure-blooded Ultraman, has he awakened the Reionics bloodline, and now has an albino juvenile Zetton named "Zetton" by his side?! With his home planet L77 and the soon-to-be-departed planet D60 both facing imminent destruction… Koul, left hand wielding the Battle Device, right hand wielding the Cosmic Beast Fist, looks at Zetton, who is also practicing cosmic fist techniques, and smiles: "Magnama alien, huh? Twin monsters, huh? I must save L77 and D60!"