Chapter 154 (Beastars)

Jack-Sensei's History Classroom (ジャックせんせーの歴史学教室) is Chapter 154 of the manga Beastars written and illustrated by Paru Itagaki, published in the Weekly Shōnen Champion of the Akita Shoten publishing house.

Synopsis
In the Cherryton Academy cafeteria, Legoshi is surprised that the academy cafeteria isn't segregated, and Jack informs him that it wasn't necessary since everyone was already sitting with their species before segregation. Returning to the subject of the special class, Jack warns Legoshi of how frightening the true history of animal society is and proceeds to ask Legoshi his height and weight. It results in measurements of a normal slender male in modern animal society and observes that the young animals around them have slender bodies. This is because that body type is a phenomenon of modern society, where the animals of this time period are getting skinnier every year and that even middle-aged animals are just the same. Legoshi corroborates by remembering that Gohin had told him that he had a beer belly and he isn't fat, and Sagwan, a sea creature, is the only chubby grown-up he has ever seen. Jack recounts that carnivores from long ago used to have a lot more fat and muscle, as well as being bigger and savage.

A very long time ago, there was a time period where the carnivores were called "life animals". Their average height and weight were 300 centimeters and 200 kilograms, and were very intelligent and had a great sense of comradery, meaning they were capable of treating their comrades with compassion, protecting them, and being kind to them. They were also very savage, and when they fought each other, they always fought to the death, and the winner would eat the loser and live on. They were called "life animals" because they would eat life and they would live only the strength of their bodies, so their population growth was stagnant and their culture was underdeveloped. However, upon encountering the "nature animals", which are now known as herbivores, the life animals perceived them as objects for their protection, which may have been their survival instinct telling them that helping the nature animals would be beneficial to them. The nature animals, who were very fertile and therefore were very prosperous, had accepted the life animals and formed an animal society. Over a long period of history, the life animals became more gentle and got more protein from eating eggs and milk, adopting a peaceful lifestyle and became thinner.

At that moment, Legoshi interrupts to point out that this period of history is the one that is always being focused on in schools and Jack informs him that this was the most peaceful period in history, since the scary stuff happened afterwards in the Carni-Herbi War that happened 100 years ago. Assuming that conflicts are something to be expected when two different species live together, the war was such a big conflict that new monikers were invented for each of them - "carnivores" and "herbivores".

In the war, the herbivores realized that their population, which was three times bigger than that of the carnivores, has declined to the point that their populations are the same, in addition to their corpses disappearing. They accuse the carnivores of using the war as an excuse to eat them, while the carnivores only beg them to surrender or else they would end up eating them, claiming not to want to destroy the civilization they worked so hard to create. They declare that they are fighting a senseless war and if they surrender, they won't be eaten, and thus they will be able to atone for this from now till the distant future. And then the battlefield is invaded by a gigantic whale so big that the herbivores stopped taking the war seriously and surrendered, ending the war. Legoshi, totally unable to believe this, responds with an awkward smile, which annoys Jack for not being taken seriously.

At the same time, Yahya is having a conference with the whale who stopped the war and who is now 400 years old. He claims no words can describe the amount of respect he has for him, and asks him what words he used to stop the war so he would get a hint necessary to help the animal society. However, the whale refuses to reveal this to him, claiming that the land animals are immature and always fighting, so they have to coexist more peacefully before he can tell him. The whale swims away, and a disappointed Yahya ends the summit meeting.

Characters

 * Jack
 * Legoshi
 * Gohin (Legoshi's imagination)
 * Sagwan (Legoshi's imagination)
 * Yahya

Important Events

 * The origin of animal society is revealed.
 * Jack reveals the hidden story about the Carni-Herbi War.
 * It is revealed that the war was stopped by the intervention of a whale.

Trivia

 * Legoshi reveals that Gohin used to have a beer belly.
 * The thinness of the animal society refers to the thinness of the Japanese population, a country with a low rate of obesity thanks to the laws of basic nutrition for its population.
 * The uniform used by carnivores in war resembles the Imperial Japanese Type 98 uniform. The herbivores' uniform resembles the Imperial uniforms used before World War I.
 * On one of the signs in the cafeteria, you can see the logo of the Akita Shoten publishing house.