As Laplace explained, Angel gradually came to understand the inside story.
When Hong Gemata led a team to explore mirror space, they encountered a mirror space containing cemetery ruins. Then, unfortunately, he ran into the cemetery's original owner, now an undead being, and ultimately died miserably within the ruins.
As for why Laplace was certain that the man with the patterned face was the undead being from the ruins—
It was because Hong Gemata and his two vice-captains had encountered the undead together, and the two vice-captains had been killed by it first.
After Laplace entered the Dream Crystal Plain, she briefly described the physical features of the patterned-faced man. The two vice-captains immediately confirmed that he was the undead being who had killed them.
"However, there are some suspicious details here."
Angel said, "Suspicious?"
Laplace explained, "According to Hong Gemata's teammates, when they searched the cemetery owner's room, they saw only the dead Hong Gemata and the bodies of the two vice-captains."
"They did not see that undead being."
"If the two vice-captains had not, after entering the Dream Crystal Plain today, both stated that they had been killed by an undead being, everyone else would have thought the three of them had been killed by the ruins' mechanisms."
Angel roughly understood. "In other words, the two vice-captains were killed by the undead from the ruins first. After they died, Hong Gemata died as well. But Hong Gemata may have done something that caused the undead being to disappear too. Thus, the people who later collected their bodies had no idea that the undead being even existed."
Laplace nodded. "That is correct. The suspicious question now is: after the two vice-captains died, what exactly did Hong Gemata do?"
Angel said, "If there is no other evidence, and we can