[Marion]

Originally Posted by Workworkwork

Absurd, but it works. Kumasawa dies of old age before the game, letting Beato worm her way in. She can just prepare her corpse, toss a stake in it, and bam, Kumasawa's been murdered by something occult.

Episode 3 had a wrench thrown in it by Kanon or someone else figuring out Beatrice was disguised as Kumasawa. They struggle, Beato gets away just barely, but she loses the stakes, which the other culprit then tosses in with the murders.

As a little consolation prize, she paints the account number on the parlor door.

Dude Kumasawa is an old woman and the Suit-Beato we see is apparently somewhere around her twenties, according to Kyrie's observations (provided she's not lying). That same woman then just switches back into being old Kumasawa. You'll need good quality makeup to fool people and being able to look that old is as probable as one of the six victims in the shed in EP 1 having good quality makeup in order to fool everyone into thing their face was impounded (seriously did you see those manga images. That can't be faked at all).

Spoiler for EP 5:

We also know that Beatrice designed her games to be solvable, unlike Lambda who just threw the book away. We get several hints on Kinzo being dead before EP 4 (he never leaves his room, only the one-winged eagle servants can see him + Nanjo, odd behavior when talking with Natsuhi, body is always burnt to a crisp, magic scenes happen around him a lot and even parents are suspicious about it) but there is nothing regarding characters being in disguise like Kumasawa.

Knox Rule 10 - Twins must be accounted for and hints must be given toward disguisers.

We need some type of hint towards Kumasawa not being Kumasawa or that she's dead, like with Kinzo.