[Metaler]

Originally Posted by Arkwright

All right, I now have the basis of a theory for what happened during the first four games.

It still needs some details to work out, but I started out with the belief that the foundation of a theory should be a narrative, story-based reasoning for why things happen, and not simply how to explain individual events.

So this is the core idea I have at the moment. I'll probably come up with specific details on the individual murders at some point but I think most of them can be understood simply with the basic idea.

Spoiler for Theory:

-Battler is Kyrie's son.
-Jessica is actually Battler Ushiromiya, Asumu's daughter.
-Battler's sin refers to something he did at Rokkenjima that caused this information to be known to the outside. Not being told the consequences of what he did, he didn't regard the event as significant.
-Asumu may have died as a result of the truth being known.
-Kumasawa is the "Beatrice" who planned the events.
-Kumasawa's past is a blank slate, and if she had a close connection to Kinzo, of the suspects she is the most likely to have a large spare sum of money and yet no particular need to hold on to it herself.
-The original plan is for the Ushiromiya family to "disperse." With the adults all in rising financial trouble, the family in general will disappear from the island under the guise of a witch's ceremony, and their remaining family members will be reimbursed.
-Ange, the only person not present at the family conference six years ago, will be "spared" and then reunited with her parents in secret after the weekend is over.
-However, "because of Battler's sin," everything does not go as intended.
-In addition to Krauss, Natsuhi, Rudolf, and Kyrie, at the least, Eva, Rosa, and Kumasawa know of Jessica's true parents. There are two factions working against each other: Eva, Rosa, and Hideyoshi, who use blackmail to threaten Krauss and Rudolf, who have the assistance of most of the servants as Krauss is the acting head.
-Since she knows George is actually the first in line of the grandchildren for succession, Eva is in a good position until the letter regarding the epitaph is revealed. Since she believes Krauss has the gold, she fears she will lose her advantage, and this causes tensions to escalate.
-Kumasawa, upset with how things are unfolding, enlists Kanon with protecting Jessica and finding out what the other factions are planning.
-The "Dispersal" plan involves a catastrophic event on the last day of the conference which will cover up the actual details of what happened. It may be an explosion, a fire, poison gas. Kumasawa warns most of the family's adults ahead of time, but due to things spinning out of control, the ones who know about the plan rarely survive until the end of the game, leaving the clueless grandchildren still left in the mansion.

This theory of yours actually makes a lot of sense, although I would include something like a "religious cult", but I don't think it would be entirely necessary. xD~
Anyway, your theory actually made me think about something: maybe Jessica was supposed to be raised as a boy, considering her personality (something about the way she talks, which makes her sound "manly").