Chapter 83

Toward the Complete Answer, Part 1 (凡テノ答へ 前編,) is the 83rd chapter of the Bungo Stray Dogs manga.

Summary
Ranpo uses Super Deduction to figure out the identity of the Decay of Angels' leader, Kamui. To begin his analysis, he utilizes Ango's initial warning: that Decay of Angels members are most likely hidden in the government. Subsequently, the Shikyū Award was conferred to the Agency upon which the government-based Decay of Angels members switched places with Kamui. Since the latter has access to secret government meetings and had the chance to allow Gogol to act as Tonan's secretary, Ranpo claims that Kamui must be a high-ranking official in the government. Furthermore, per Sigma's memory information, Kamui only appeared to him wearing a gas mask, quite possibly to hide his recognizable, well-known identity. With these factors, Ranpo has a hint on Kamui's most possible real identity.

Eventually dropping his drink in shock of his newfound knowledge, Ranpo conjures up a penultimate deduction: Kamui is an extraordinary ability user who controls powerful ability users alike such as Gogol and Dostoevsky, which means Kamui possesses an advanced level of skill and charisma way higher than his cohorts. Lastly, Ranpo deduces that Kamui targeting the Armed Detective Agency to carry on their sin must mean that Kamui has a connection to or are involved with the Agency. Only one person fitting such description — part of the government's top brass, a well-known celebrity figure, someone who benefited most from the terrorism incident, a very powerful ability user surpassing even Dostoevsky, and someone with relations to the Agency — comes to Ranpo's mind, who turns out to be Fukuchi. With Ranpo breaking out in a sweat given only a split-second decision, Ranpo comes up with a way to try and turn things around from the man whose help they depended on.

Trivia

 * In the flashback showing Ango state that Decay of Angels members are possibly hidden in the government, this chapter depicts him wearing his jacket, though he was not wearing one in the chapter when he said the warning.