Originally, there were no ghosts on the Blue Star.
Once, a pilot dropped a "Little Boy" on Japan, and he lived to a ripe old age of ninety-two. This is proof that there were no ghosts on Blue Star.
But now, with Spirit Power Awakening, some wicked things have resurfaced.
Moreover, the Skuru people have also used the "Spiritual Spring Eye" to create a plethora of monsters, like the creatures in "Ultraman" and the horrifying deep-sea creatures from "Pacific Rim," all of which are now appearing on Blue Star.
Of course, these large creatures would only gradually emerge a few months later.
At this stage, the Skuru people could only create a batch of ghosts, wreaking havoc in the world of Blue Star Humans.
The native ghosts, coupled with the manufactured foreign...or rather, extraterrestrial ghosts, collectively formed the main threat to the Blue Star Humans in the first three months.
What Su Yu is doing now is to try to eliminate as many ghosts as possible.