The mystery of Sora’s disappearance continues. The only one who still remember him is Shiro. Stephanie and Jibril are still Shiro’s subordinates, but history has been rewritten as if only Shiro ever arrived to this gaming world.
In a chess game, Jibril asks Shiro to lose. And when Shiro is about to do that, she remembers Sora’s word telling her that blank (Sora and Shiro as duo) never loses. Next, Shiro discovers that they can’t remember anything from the previous day, so an entire day is erased from their memory, along with all memories about Sora’s existence.
Thanks to Stephanie who accidentally fell and reveal 3 othello pieces, Shiro finally figures out what happened. Sora were playing a game against Kurami (and the elf named Fil). The othello is a memory flipping game. Each time an othello tile is flipped, a piece of its player’s memory goes to the opponent who flipped it. Sora played it in such away to allow Kurami to flip a lot of his pieces, resulting in Kurami getting Sora’s memories. The moves are planned in such away that the Shiro can turn back the situation using the last remaining 3 pieces and win the game. That brings Sora and Kurami back.
Sora’s winning requests are to return the memories to each other (his own memories and Kurami’s), but each of them retains a copy of others’ memories. With this, now Kurami knows (almost) everything about Sora as she has “peeked” into his mind while playing the game. This was Sora’s grand plan to get Kurami and Fil into their team willingly.
To me, the best part of this episode is the last scene when Sora and Shiro are crying together, and Kurami and Fil do the same. I think it’s a sweet way to show the strong bond between those two “pairs”.