The Rule of Thumb of Humans Seeing Ghosts in Super Sentai
Gokaiger 28 does leave me pretty mixed since the reason that Gai Ikari can't see Gai Yuki was never revealed and the former only assumed because he was human. In fact, it could be funny to assume that the comedic scene to others happened because they share the same first name. So what's really the rule of thumb of ghosts and humans in Super Sentai?
So why could the first five Gokaigers see Gai Yuki as a ghost and Gai Ikari can't?! The possible explanation is because of their alien heritage but then there were supposedly normal humans who can see ghosts.
Ryu Tendo during his wedding day while stupidly he couldn't see Gai Yuki slipping away from life... he was able to see Rie Aoi's ghost bid him farewell and giving her blessings. Before Jetman ended, he saw Rie Aoi's ghost one more time before he eventually let go. So was Ryu Tendo blessed with the ability to see ghosts while the rest of his team weren't despite the birdonic waves? Possibly. Now only if Toshihide Wakamatsu would reveal those apparent plotholes in Jetman and Gokaiger concerning ghosts and humans. So it's possible he could see Gai Yuki's ghost as well as the other ghosts since he did fight side by side with a ghost during the Legend War.
In Zyuranger, Burai's ghost appeared to the Zyurangers and they could see him. Assumption is because of their heritage as super humans they could see his ghost. Others may never see him. Then again, Gai Ikari saw his ghost but never unmorphed. He was also seen by the others during the Legend War despite being a ghost.
Meanwhile the bigger plothole was that did Gai Ikari die and come back to life? Not stated whether he did or it was a near death experience? In the episode where he becomes Gokai Silver, he saw the ghosts of Mikoto, Burai and Naoto (only Burai unmorphed though)... but later he could not see Gai Yuki. These people fought side by side with their still alive comrades during the Legend War, which leaves again the question of what's really the rule of thumb of ghosts seeing humans in Super Sentai.