Dichotomatic Timeline: And Then There Were None

[King V]

Events:
By the time of Koishi's death, there were only 10 people left on the island. Mystio, Blitzcrank, Bobby Fullbright, Iris Ashberry, Shiori, Spw W, Ririchiyo, Dr. Faust, Kouta Tsuchiya, and Ai Emna remained.

On the day of Koishi's death, at 4:30pm, two more people were found dead in the Dining Room. Kouta and Spy W were found hanged by the chandelier with a single rope between the two. Before this happened, most people were locked in their rooms. Both victims' rooms were investigated, and both doors were found locked. The Master Key was used to open both, and inside the victims' room keys were discovered on the beds... in the opposite rooms. Mystio confirmed both doors were locked before opening them with the Master Key. All windows were also locked from the inside.

Victims: Kouta Tsuchiya, Spy W
Cause of Deaths: Strangulation
Time of Deaths: The bodies were found at approximately 4:30pm
Locations: Both bodies were found in the Dining Room

Around an hour later, Iris, Dr. Faust, and Ririchiyo left on a trip to the Dock to see if they could find help. Three hours passed before both Iris and Ririchiyo came back to the mansion to report that Dr. Faust had died. His body was found near the beach, a large blunt wound on his head. Iris and Ririchiyo reported that they had been together the entire time, and that Dr. Faust volunteered to go to the Dock before them to scout the place out. When he hadn't returned for over 30 minutes, they decided to look after him and found him dead.

Victim: Dr. Faust
Cause of Death: Blunt Force Trauma
Time of Death: Approximately 8:30pm
Location: The body was found at the Beach

Everyone went to sleep uneasy. When they woke up and headed to the Dining Room for breakfast, they found Ai Enma lying on the table. Her body had no visible injuries, but Shiori reported after an examination that she was dead. Poison was suspected as the main killing agent. Once again, the victim's room was searched, and the victim's room key was found inside. All windows were locked from the inside, and Mystio confirmed the door was locked before opening it with the Master Key.

Victim: Ai Enma
Cause of Death: Poison
Time of Death: Suspected to be late at night, the body was found at 8:00am
Location: The body was found in the Kitchen lying on the table

Growing even more uneasy, everyone decided it would be best to move in groups of 2. However, just 3 hours later, Blitzcrank reported that he saw both Mystio and Ririchiyo lying on the ground in front of the Mansion. But somehow, nobody could find a way out of the Mansion. The front door had been locked by key, and all the windows were confirmed to be bolted shut from the outside. Finally Bobby Fullbright broke a window near the entrance and everyone headed out. Shiori and Blitzcrank examined both the bodies. There was a large hole in each of the victims' chests, like they had been shot. Blood was splattered everywhere on the ground. Shiori confirmed that the Master Key was in Mystio's pocket and she then took possession of it. Blitzcrank confirmed that Ririchiyo had no items on her.

Victims: Mystio, Ririchiyo
Cause of Deaths: Large holes in the bodies, seems to be gunshot wounds
Time of Deaths: Both bodies were discovered by Blitzcrank first when looking out the window at 11:00am, then after searching the mansion, 30 minutes later Bobby Fullbright broke down the door and everyone ran over to the bodies at 11:30am
Location: The bodies were found lying near each other at the Mansion Entrance

Only 4 people remained, Iris, Bobby, Blitzcrank, and Shiori. These 4 decided that instead of just waiting around, they should head to the Dock to get off the island. These 4 immediately headed out, but as they reached the dock they couldn't get the gate open. Bobby and Blitzcrank volunteered to go to the Hidden House to retrieve the key for the Dock and they left. An hour later, only Bobby returned. He said that Blitzcrank had gotten ahead of him and that he had lost sight of him somewhere. Then when he had reached the Hidden House, he saw Blitzcrank lying at the bottom of a cliff with his head smashed against a rock. Had it been an accident?

Victim: Blitzcrank
Cause of Death: Blunt force trauma from falling down a cliff
Time of Death: Approximately 1:15pm
Location: The body was at the bottom of the cliff near the Hidden House

The remaining 3 people headed to the Dock, locking the gate behind them. But they found to their shock that all the boats had been smashed and were now unusable. At this point, there was a disagreement. Bobby decided to brave the storm and head back to the mansion, but Iris and Shiori wanted to remain at the dock in case of a ship coming back. Bobby headed off leaving Iris and Shiori there. Around 4 hours later, when it was apparent that no ships would be coming back, Iris and Shiori had no choice but to head back to the Mansion. Then both found in front of the Mansion Entrance, next to the corpses of Mystio and Ririchiyo, Bobby Fullbright was on the ground dead. He had a similar wound to the two, a hole in his chest similar to a gunshot wound.

Victim: Bobby Fullbright
Cause of Death: A large hole in the chest, seems to be a gunshot wound
Time of Death: The body was found at approximately 5:30pm
Location: Lying near the mansion entrance next to Mystio and Ririchiyo

Only Iris and Shiori remained now, and they cautiously went up to their rooms. And then, during that night, nobody was left alive on the island.

========================================================================================

Darius and Erika landed on the island on a boat. They walked towards the Mansion, and headed up to the guest rooms.

"Look at that, Shiori is dead. She's lying in the entrance to her guest room. There's what looks like a gunshot wound in her chest, and she's bleeding all over the place."

"That's not all. Iris Ashberry is also dead. Her guest room door is locked, and so are all the windows in her guest room. Her guest room key appears to be lying on top of her bed. She's been hung by a rope, the cause of death is strangulation."

"Hah, with just this much evidence, the great detective Erika Furudo has already determined the culprit's identity!"

"You never shut up, do you? Anyways, it's time to leave. We have a game to attend."

"You mean you have a game to attend, I have to attend to master Bernkastel."

"Is there even a difference?"

"Of course! But I agree we've spent enough time here. Let's go."

And then the detective and demigod of truth left the island, and the story was completed.

Now, I'll give you all a huge hint, there is only 1 murderer for this murder series. Can you figure out who?

[Ravan]

Beep boop. One of the people to have supposedly died must have survived after all. If not that, then a series of traps was left behind by one of the dead for the remaining survivors, thus leading to the rest of our cadre's untimely deaths.

Repeat it in red. "Everybody on the island has perished." Humans are capable of making errors, and there is always the possibility that they overlooked something, misunderstood something, or hid something when it came to the corpses. I would like you to confirm whether or not any mistakes were made with the death reports as well.

[King V]

All humans on the island with the exception of Erika and Darius are dead. Erika and Darius are not the culprits nor are they related to the murders in any way except for providing information.

[Ravan]

The answer becomes clear to me now. The culprit is not human. Which means that we have all been outwitted and outsmarted by a higher being.

Yes, I am referring to the obvious. A bear. Clearly the bear was capable of punching a great hole through people's chests as well as strangling them and brutally beating them to death with its paws. A bear is not a person, so I see absolutely no flaw with this logic whatsoever. Am I wrong, or am I wrong?

[King V]

The culprit is human. No non-human entities were involved in the murders on the island.