When I first saw Midari with her eyepatch, I assumed combined with the piercings and arm bandages that she was simply fusing Chuunibyou and delinquent aesthetics into her personal style. But the eyepatch is functional, covering up the fact she has no left eye.
In the past, Midari was a gifted gambler, but never found any happiness from her victories or the doors it opened. So when she ran herself into nearly $3 million in debt, President Tsubomi offered to buy her eye for just the amount she owed.
Before a surgery can be arranged, Midari gouged out her own eye right there, intriguing Tsubomi enough to call them square and offer a place on the council, which Midari eventually took.
From that self-eye-gouging moment, Midari learned what it was could fill the hole in her heart: the pain and fear of dying she gets from her particular brand of gambling. In her three-round cards-and-pistols game with Yumeko, she wins the first round, but loses the second when Ryouta realizes he should arrange the cards exactly the way Yumeko did, because that’s what he believes she’d want him to do.
When it’s Yumeko’s turn to fire, she doesn’t have the slightest amount of fear of either dying or kiling Midari. For one thing, she can tell from the slight difference in weight that she’s holding her own gun, which has no bullets. That leaves them tied, one game each.
In the final round, Ryouta notices that the image of the two players is reversed on his monitor, and accuses Midari of cheating, but Yumeko saw through it all along, as Ryouta’s image was also reversed, and she played accordingly. Furthermore, Yumeko is not amused by this dull trickery, which seems intended to assure that Midari loses the game.
Midari is trying to get that feeling of gouging her own eye out, spurred on by the President who will never have her. In Yumeko she sought a “schemer” like Tsubomi who she could count on to “dominate” evry part of her her in every way.
She ultimately wants Yumeko to kill her, unsatisfied with Tsubomi’s promise to eventually do so. Suffice it to say, Yumeko won’t play this game, not because it’s morally repugnant, but because Midari is being selfish by trying to hoard all of the pain for herself.
In Yumeko’s ideal, both sides feel death’s cruel skeletal fingers scratching at their door. In this rather rote S&M scenario, it isn’t even that Midari expects Yumeko to get off on dominating her…she simply doesn’t care if or how Yumeko at all; only whether she, Midari, gets her pain, release, and death. Yumeko gets nothing, and that pisses her off, flashing her scariest face yet.
With the third round complete, ending in a draw (Yumeko chose all her cards wrong to thwart any chance of winning), she gets up and walks out, their business completed. And while Midari got off one more time from Yumeko’s utter rejection, it looks like that will be the last time ever, if Yumeko has anything to say about it.
We’ve never seen Yumeko as angry about something as she is at Midari, and it speaks to her fundamental humanity in spite of her seeming super-human senses and gambling skill. People like Midari piss her off most because they’re only in it for themselves, while Yumeko’s happiest moments occur in which someone else gets something out of it, whether it’s a stern lesson in not underestimating her, a shot at redemption, or simply a shared joy over a gamble well-played.
This is why despite getting all worked up in Midari’s dungeon, Yumeko is back to her pleasant self, and I don’t even think she’s putting on a mask. Instead, she seems to take solace in the fact that Ryouta was there with her, and the two were in sync enough to foil Midari’s underhanded, self-destructive plans. I don’t think Yumeko is stringing Ryouta along. I think she values his friendship, and treats him how he treats her: with kindness and respect.
Oh yeah, also, Mary utterly refuses to join the student council, and Tsubomi can believe whatever she wants is the reason, Mary won’t tell her. Of course, we know why: while one could argue that having an “inside man” on the council could be useful in an inside-out rebellion, it’s just as likely the council would change her than vice-versa.
Instead, Mary won’t legitimize a council that treats “livestock” like an inferior race and uses life plans to practice eugenics. She’ll seek a way to destroy it from the outside.