Gaiden Chapter 1

The Old Ravine Cathedral / Noon / Sunny ① (山間の旧礼拝堂／正午／晴天 ①,) is the first part of the 1st chapter of the Bungo Stray Dogs Gaiden manga.

Summary
Inside a cathedral, Ayatsuji reveals that the culprit is inside the cathedral. The people inside the church were shocked to hear about the revelation. Ayatsuji then states that there are 68 children in the school however one of them was deliberately chosen and their breakfast was poisoned and thus result in death. A man then steps forwards and clarifies if the cause of the death was a prick from a poisoned apple and not from the food. Ayatsuji replies that it was a cover-up and that before the boy's death, the culprit pretended to help him while he was poisoning and stabbed him then and that the symptoms including dilated pupils, limbs were paralyzed and difficulty breathing was clearly from a poison that targeted the nervous system.

The man then tells Ayatsuji that it was random who served the food and would it be possible to poison only a single child. Ayatsuji replies that it is possible and describes it as occam's razor, in which the simplest theory is most likely to be the truth. He then further explains that in the boy's case, everyone was served with poison and the only target would only be killed and tells that the poison used was a deadly toxin enough for one gram to kill million people. He then further explains the culprit's plan which is the evening before, the culprit applied an adhesive layer of poison to all tableware. The culprit then deliberately made the victim leave his heat by reprimanding him for the action the culprit set up.

Another man approaches and says the name of the toxin, botulinum toxin. Ayatsuji then tells that the culprit interrupted the victim's meal and called him away from his seat and an uninvolved third party wrapped the meal causing the anaerobic bacteria to produce to poison and was turned into a poisonous meal. Hearing this, the people inside the cathedral turned their heads to the coaching teacher who was the one who reprimanded the victim. However, the coach denies it. Ayatsuji also says that he is not the culprit and tells that the culprit made an alibi and the person who falsely accused the victim of the robbery, it was the teacher.

Shocked by Ayatsuji's statement, the teacher began panicking and asks why would he do such a thing and there is no evidence. Ayatsuji then tells him the small needle he put on the sole of his shoe will lead to the dish he hides in the mountains. The teacher then panics. Just then, Tsujimura appears at the front of the cathedral and tells Ayatsuji not to accuse criminals without permission. However, the teacher begins to run away and approaches the door.

Character in Order of Appearance

 * Yukito Ayatsuji
 * Mizuki Tsujimura (debut)