Ultraman S01 E25 Mystery Comet Tsuifon

"Protector of the Universe."

When a comet comes dangerously close to the Earth, the heat may have caused an unexploded nuclear warhead to detonate. When they come up empty in the search they assume a monster has swallowed it. They end up facing off against 3 monsters, but it's the new Red King that has the bomb stuck in his throat and stopping this mega Royal Rumble may not be so easy.