“I should have never posted the video. I should have put the cameras down,” he said.

The original video, which has since been removed from YouTube but is available elsewhere online, begins with Mr. Paul warning viewers that the following footage is graphic.

“This definitely marks a moment in YouTube history,” he says. “Because I’m pretty sure that this has never hopefully happened to anyone on YouTube ever.”

“Now with that said, buckle up,” Mr. Paul adds, cursing for effect.

As the video proceeds, Mr. Paul describes the reputation of the Aokigahara forest, which has become well-known in the past decade as a destination for people looking to kill themselves.

In 2016 alone, three North American films were set in the forest, which lies at the base of Mount Fuji, a sacred site in Japan.

Local folk tales have also fueled talk about the paranormal within the forest, a subject that Mr. Paul eagerly latches onto as he and his companions begin their trek with a guide.