There are also rumors that:
SCROLL BELOW FOR POSSIBLE SPOILER!
Mefilas may show up towards the end of the series to clash with Ultraman Mebius. I really hope this is true. I've been waiting for a proper return of Mefilas since his original Ultraman episode. The other episode he showed up in with another Ultra series is complete garbage so I personally don't count it has is "official return" though I'm sure it's cannon per Tsuburaya.
From reading over at Lah, the final episodes may involve some very strong seijin that battle Mebius and he is helped by the Ultra brothers.
Perfect time for the original Ultraman to come to Mebius's rescue and then
continue his battle with Mefilas from the original episode!
I could imagine it going something like this:
After Mefilas has basically beaten Mebius, we see a red orb descend
from the sky over Mebius's lifeless body.
Mebius's body rises into the red orb is brought in front of Zoffy whom says Mefilas is too tough for the "young Mebius" to beat alone and then summons Ultraman.
Zoffy
Mefilas-Seijin has returned to Earth and I have summoned you, Ultraman, to face Mefilas once again. You fought him bravely many years
ago to defend the Earth and it's people and you are now needed once
more. Go forth now Ultraman and defeat Mefilas!
We see a brilliant flash of light and then see Ultraman standing in front of Mefilas. The rematch we've been waiting for is about to take place!
Mefilas
Finally, we meet again Ultraman! When we first met, we were evenly matched. Now we will find out who is indeed the strongest. My prize-The
Earth and it's people I will rule over! Hahahaha!
Ultraman
You will never defeat me! The Earth and it's people are noble and peace loving, as we Ultramen are! I will not permit you to take over their Earth!
Let us finish what began many years ago Mefilas, let me show you the
true power of Ultraman!
Kind of corny I know but I'd love to see something similiar.
