Weak Square (
While making plans for their next move, Sora and Shiro have difficulty finding information about their opponents. Meanwhile. Stephanie tries desperately to beat them in games, only to end up defeated and humiliated. After a while, they learn that Elchea's library, together with nearly all of it's wisdom in books, was in possession of one of the Flügel, after winning it in a game from the previous king. They then decide to challenge the Flügel and take the library back.
The following characters are listed by the order which they appear in.
- Speaking roles
- Non-speaking roles
- Minister of Economy
For games, the challenger is listed before the challenged party.
- Match of Blackjack between Stephanie Dola and Sora
- Result: Sora wins
- Match of poker between the siblings and the opposing ministers
- Result: The siblings win
- Match between Stephanie Dola and Shiro to guess the gender of the people who pass the alleyway, best out of ten (result was 1-9)
- Matches of Ghost Leg, Spicy Russian Takoyaki (adapted from Russian Roulette), The Game of Life, and rock-paper-scissors between Stephanie and Kuhaku
- Match between Stephanie and Sora to guess how long a bird would stay on the roof
- Result: Stephanie loses in all matches
- The siblings and Stephanie show up at the library and the Flügel makes an appearance.
Key differences from light novel
In the light novel,
- Sora and Shiro did not move out into a new home. They first demanded for the construction of a new wooden house, after Shiro had rolled off the bed.
- The opposing ministers did not just lose their titles, land, money, and holdings, they also lost their families in the bet. Sora let these family members do as they please, and contemplated if they would forgive the ministers who idiotically wagered their family's lives. 
- When the siblings ran off, Stephanie's leash was not tied to a pole, but left on the ground.
- The random game matches in between the two guessing games did not occur, so Stephanie was not stripped of clothes as much or bespectacled, and Shiro did not have as many extra items to wear.
- The episode title's katakana has a different meaning from its kanji. The katakana (グランド・マスター) reads 'weak square', while the kanji (駒並べ) means 'arranging the pieces' i.e. 'setting the board'.
- A "weak square" is a chess term. A square is weak when it is controlled by your opponent and you have little or no chance of regaining control due to a lack of pieces which can effectively fight for that square.
- There is a clear parody of the movie Castle in the Sky. The main characters are dressed up very similarly to Castle's, they mention Laputa, and say Barusu (censored) as they hold hands, the word of destruction spoken together by Pazu and Sheeta in the climax of the film.
- Music from Mario Party is played while Sora is explaining probabilities with cards.
- This is the first episode which the former king of Imanity shows his face. He greatly resembles a King poker card.
- In the post-credits scene, Stephanie reverts to only having her panties taken away by Shiro and keeps her other clothes. This is probably for consistency in the events that would happen in Materialization Shiritori, as her other clothes were never taken away in the light novel, and the fact that her clothes could not be returned to her under the Ten Oaths. Shiro also reverts to only wearing Stephanie's panties on her head.
- When Stephanie Dola is complaining about the lack of activity as king and queen of Sora and Shiro, they reply to her that the "Blanks" won't work by nature. The way they explain it is similar to the way Simon (of the anime Gurren Lagann Tengen Toppa) explains to the main antagonist the potential of the mankind.
- Screenplay: Aoshima Takashi (あおしまたかし)
- Storyboard: Sayama Kiyoko (佐山聖子).
- Director: Sasaki Sumito (佐々木純人) and Watanabe Kotono (渡邉こと乃)
- Animation director: Ichino Maria (市野まりあ) and Nagayoshi Takashi (永吉隆志)
- Light Novel Volume 2: Chapter 1, Part 3
- Light Novel Volume 2: Chapter 2, Part 2