Morito watches the moon rising in a pensive mood as he walks on fallen leaves outside the fence of his house. Usually this activity takes far too long, but tonight he is horrified with each passing second because it brings him closer to his shocking destiny - he will be a murderer by morning's light. Worse, he must kill somebody that he does not hate.
He must kill Kesa's husband, Wataru Seamonno-jo, a handsome, passionate, and determined man, who undertook to learn to write poetry simply to win Kesa's heart. Morito contemplates whether he really loves Kesa after all. He had a desire for her before she married Wataru, but now admits that they may have been mostly a prolonged sexual urge.
After three years of their marriage, Morito succeeded in meeting her in private, and furthermore, in taking her body as he had desired as well. His desire for her weakened immediately, because "she was not what [he] expected her to be" (loc. 753). In fact, she was much worse. Her face had lost its bloom and smooth charm, with dark circles around her eyes. Yet, he could not look away.
She tried to describe her extreme compassion for her husband, but he suspected it to be a lie. Even now, as he speaks to the reader, he can see how somebody might call it a product of his own conceit to consider Kesa's love to be a lie, but he feels the same as ever about it.
He pulls her up and sees her messy hair and sweaty skin - things that "indicate the ugliness of her mind and body" (loc. 763) to him. At that moment he realized his hatred for her, yet in spite of himself, he could not help from whispering his compulsive thoughts: "Let's kill Wataru" (loc. 763).
He wished to disgrace her and what better way than to kill the man she apparently loves so much? This is his thought-pattern, though he cannot agree with it anymore and even blames a demon for having contaminated his mind.
Finally, she agrees to his whisper. A mysterious sparkle appears in her eye and Morito regrets that he can no longer take back his proposition. He fears that she might take revenge on him and kill him if he failed to carry out his part of the bargain. He cannot determine whether he despises, fears, hates, or loves her anymore. A ballad about the darkness of the human mind comes out of the night.
At night under a lamp, Kesa stands facing away from the light. She fears living another day in shame and evil, but feels confident that Morito will come, because he must be afraid of her. She recalls the day when she met Morito in her aunt's house and how his eyes "showed [her] [her] ugliness mirrored in his mind" (loc. 806). She could not endure her own loneliness having seen her ugliness so vividly and so surrendered herself to his desires.
She recalls sobbing through the whole event and that when he had whispered in her ear, she was "strangely enlivened" (loc. 817), despite her love for her husband. Just then, she saw the smiling image of her husband's face and decided that she must die herself. It is the only way to revenge herself on Morito’s wicked lust.
Having made up her mind to kill herself instead of allowing the death of her husband, she forced a smile and repeated Morito's whisper. He may have no idea, but tomorrow, it will be her body that is headless.
This is a much darker story than many of the others, more aligned with "In the Grove" or "Rashōmon" than the bittersweet "Yam Gruel" or "The Dragon." Written in a format that conjures a theatrical setting more than a novelistic painting, we begin with Morito's monologue under the moonlight and go on to Kesa's shorter monologue under a night lamp. It also proves itself to be the most psychologically thrilling of all the stories, despite its relation to an original text from the 1400's The Rise and Fall of the Genji and Heike. If one should need proof that Akutagawa is a master of retelling classical stories with modernist psychological terms, "Kesa and Morito" can be called upon.
In the original text, Morito is a palace guard and Kesa is a court lady. Kesa yields to the violent Morito, who is in fact her cousin, in order to save her mother who was also threatened by Morito. When he comes to kill Wataru, Kesa has rearranged the living spaces and tied up her hair so that Morito will mistakenly kill her instead of him. Morito goes mad and becomes a Buddhist ascetic. This original story was also adapted into the 1953 film Gate of Hell (Jigokumon).
However, Akutagawa focuses on the complex motives of both Kesa and Morito, changing the story to exclude Kesa's mother. In place of this, he gives Kesa vanity and ambivalence towards Morito. Morito, being equally ambivalent toward Kesa, is unaware of her feelings toward him. If anything he assumes that she simply doesn't feel strongly about Wataru or himself, despite her long monologue about her love for Wataru.
The nighttime seems to operate as both a sanctuary for private thought as well as a doomed and abstruse nightmare where the characters fully realize their societal expectations. The characters are both capable of perfect rational thought, and yet cannot escape their obvious logical flaws. Morito is selfish and fearful; Kesa is shameful and revengeful. If it were not such a perfect combination of characteristics, they could simply forget about the whole ordeal and move on even happier than before the affair. A reasonable man such as Wataru should surely be able to come to an understanding with his wife, whom he would rather have alive and loved than dead for vanity. Likewise, Morito's ambivalence could be substituted for indifference rather easily if he was not so afraid of Kesa's revenge.
Unfortunately though, the ending is made inevitable as the moonlight seeps from Morito's place of contemplation through Kesa's shutters.