Episode 50

Skyfall (stylized as SKYFALL), is the 50th episode of Bungo Stray Dogs anime series and the thirteenth episode of the fourth season. It aired on March 29, 2023.

Synopsis
Teruko goes head-to-head with Sigma. Tachihara rethinks the Agency's innocence after re-infiltrating the Port Mafia.

Summary
Teruko and Tachihara flee from the casino hotel guests trying to attack them for Sigma's bounty. After having altered her own age and Tachihara's, Teruko acquires intel from unknowing casino guards on controlling the central control terminal. In Meursault, Dazai is dubious of Fyodor's reasoning on Sigma being the strongest as an amnesiac; Fyodor rebuts that Sigma is above anyone else and reveals that he was written into the Book three years ago and given a home that is Sky Casino.

Teruko confronts Sigma in the comms room to retrieve the terminal key, though Sigma easily tosses it to her. Pledging to himself to stop the Hunting Dogs from saving the casino despite admitting to being an ordinary man himself, Sigma opens fire at Teruko using twin turrets and later his personally modified Directional Resonance Gun armed with his determination, both of which she withstands. Atsushi hears the fight and deduces the Hunting Dogs to be clashing with Sigma; Kyōka directs him to head to the battle.

As she gains the upper hand, Teruko avows the Hunting Dogs' own determination as the manifestation of the country's order. She then holds Sigma down at the casino's edge and issues him an ultimatum to surrender; he refuses and claims that an ordinary man can overcome any wall with enough desperation, though Teruko asserts that beyond that wall is a battle with equally desperate geniuses. Choosing to save the casino, Sigma grabs Teruko and falls with him in mid-air.

As she grapples with and ultimately leaves Sigma to fall alone, Atsushi saves him to get him to talk about the page's location. With Ango on standby to interrogate Taneda's attacker, Sigma yields, having not found his reason for being. Not long after, however, Nathaniel surfaces to attack Sigma and later Atsushi when he tries to save Sigma from falling over. Dangling in dire straits, Atsushi does not allow Sigma to let him go, not wanting him to die oblivious of his own reason for being.

Eventually, Sigma remarks on Atsushi's kindness and, claiming that he did all that he could as an ordinary man, lets go of Atsushi's hand. Ango directs Lucy towards Atsushi mid-air, where she jumps off the ledge to transport him and herself to Anne's Room. Upon successfully landing in the dimension, Atsushi saves Lucy from Nathaniel's blood bullet that grazes her. Atsushi grows troubled with fighting Nathaniel, but Lucy is confident in his loss, revealing that Anne cannot be harmed inside the dimension. Nathaniel is dragged into her secret room, and Lucy turns joyful at their victory.

However, Ango notes that they lost; from letting Sigma die and losing their only lead toward locating the page to the Hunting Dogs witnessing Atsushi saving a perceived fellow terrorist, he declares that they played right into Fyodor's hand. Dazai becomes challenged with Fyodor's play despite the latter asserting not having done anything except pray to God. Dazai then figures out that the coin bombs were also a possible decoy to draw the Hunting Dogs and the Agency to the casino.

Tachihara finds a flash drive containing Atsushi's revelation about the Decay of the Angel's theft of the page and their terrorist plan. Fyodor meanwhile notes the necessity for perfection and harmony when he wrote on the page that law enforcement and investigative bodies should dismiss any evidence about the Agency's frameup. As Tachihara breaks the flash drive, Teruko assigns him to infiltrate the Mafia again to gather intel on the missing Tanizaki and Kenji.

Tachihara recalls his hospital visit to Hirotsu and Gin, where he asked Hirotsu whether he is suitable to be in the Mafia, earning Hirotsu's and Gin's laughter. Dazai likewise laughs at Fyodor's remark and retorts that the world is run by those who act amidst incidental storms in the face of God's coincidences and absurdisms rather than those who value perfection and harmony. Hirotsu responded that Tachihara is Mafia among the Mafia and is a paragon for them.

Coming to terms with his own motive for joining the Mafia, Tachihara resolved having joined to become someone far from being his brilliant brother nor his opposite, the reason why he spared Yosano during their previous confrontation before she apologized to him. With the Mafia's belief that the Agency is innocent, Tachihara finally realizes that the Agency is innocent.

With the page's influence on him as a Hunting Dog wearing off due to his re-acknowledgment as a mafioso, Tachihara claims that they must persuade the government of having caught the wrong people. Dazai shares Fyodor's sentiment that humans are indeed foolish but refutes that they are not as boring as he thinks. Meanwhile, nearing his final falling spot, Sigma notices Nikolai, alive and well, awaiting him. The clown then mirthfully prepares to perform some of his resurrection magic.

Manga and Anime Differences

 * When running away from the Sky Casino guests, Tachihara uses his ability to open the door's lock. This was originally in the manga.
 * During the guests' hunt for Tachihara and Teruko, one of the guests asks the old woman (Teruko disguised) if she wants to join the game of tag. This was omitted in the episode.
 * Sigma's past from wandering to escaping from a human-trafficking ring was omitted.
 * Sigma originally states that he envies Teruko's eyes and expresses strong emotions. Sigma did not relay this in the episode.
 * While being dragged by Anne, Hawthorne originally tries to resist, mumbling words. This was not shown in the anime.
 * Ango further expresses his worries and anxiousness after their failed plan was not shown in this episode.
 * Tachihara originally tells Gin and Hirotsu that he is leaving after the visit because he has some other work to do, to which Gin asks what it is. This is omitted in the anime.
 * In the manga, Jōno approaches Tachihara after he purposefully misdirects her shot towards Yosano. This was omitted.
 * Mori giving the Black Lizard a briefing was originally a thought Tachihara thinking when he was searching for the Agency at the Sky Casino.

Trivia

 * Nikolai's voice actor, Takehito Koyasu, is listed in the ending credits that roll before the post-credits scene, which hints at his eventual appearance after the credit roll.