Which Story Arc Is Covered In Mushoku Tensei Volume 13?

A witch who has lived for thousands of years has grown bored with her own life and decided to leave it. Since she is an immortal, her soul cannot leave the world. However, what she can do is transfer her soul to another body. By a stroke of luck, she happens to enter the body of a princess. She was considered a miracle because when the Empress gave birth to her, the princess instantly died, along with the Empress. What the witch didn't know was that she has entered such a predicament. She has to endure the love of the cruel Emperor and possessiveness of the crazy twin princes! What will her life be at the hands of such a loving family? In addition, it seems that this body contains mana that was lost in the royal family centuries ago!

Evy was a simple-minded girl. If there's work she's there. Evy is a known workaholic. She works day and night, dedicating each of her waking hours to her jobs and making sure that she reaches the deadline. On the day of her birthday, her body gave up and she died alone from exhaustion. Upon receiving the chance of a new life, she was reincarnated as the daughter of the Duke of Polvaros and acquired the prose of living a comfortable life ahead of her. Only she doesn't want that. She wants to work. Even if it's being a maid, a hired killer, or an adventurer. She will do it. The only thing wrong with Evy is that she has no concept of reincarnation or being isekaid. In her head, she was kidnapped to a faraway land… stranded in a place far away from Japan. So she has to learn things as she goes with as little knowledge as anyone else. Having no sense of ever knowing that she was living in fantasy nor knowing the destruction that lies ahead in the future. Evy will do her best to live the life she wanted and surprise a couple of people on the way. Unbeknownst to her, all her actions will make a ripple. Whether they be for the better or worse.... Evy has no clue.

Al, was thrown into another world for no apparent reason. A new world filled with magical things. However, this wasn't the first time he had been reincarnated. He thought he was just an ordinary youth, but it turned out that his identity was so extraordinary in his first reincarnation. There were his harems still waiting for his arrival. Will he meet them soon and what will happen?

A thirty-year-old office lady, who got into an accident and is now trapped inside a novel series she loves. She was reincarnated into one of the side character extras of the story and meets in person the tyrant magician, the playboy prince, and the clueless female lead of the story.

A Luna was reincarnated in two separate bodies, and her fate was divided as a result of the curse that she carries from the past. One of the bodies will usher in an era of tranquility for the human race, while the second will usher in an era of calamity for her kind! However, to make the soul whole again, One of the two bodies needs to give up her life to save the other; otherwise, both of them would perish. So, who would die for who, and why?

When Mizuko slipped into the other world, she landed in the arms of a mischievous demon prince, Kenshi. New to the world, she didn't know he was a demon as he looked to her like he was a decent person. Because Kenshi helped her first, Mizuko decided to ask him for help in finding a way home while she fulfills the dead mage's request in relaying the message to the King. But no demon in Souzou helps unless they get something in exchange. A promise, it is what Kenshi wants the most.