Ah, yes. The reset button. I figure that if you're going to kill someone, kill them. If they're not going to stay dead, keep it ambiguous and uncertain. "Yamapapa has been missing for sometime now. We're not sure what has happened to him. We believe he may have been kidnapped." Blah blah blah, stuff happens. "Yep, since Byakuran's existence has been wiped out, Yamampapa has also returned. It turns out that Byakuran was keeping him in a meat locker... for fun."

The weird part of it all? Yamapapa should be dead in THIS world, which should technically cease to exist when the gang goes back in time. I mean, Yamapapa isn't dead in the past, so I always figured that that wouldn't even be a problem because Byakuran would be stopped and therefore, Yamapapa would never even be killed in the first place.

Amano, you fail at time travel and making sense.