Third season of Isekai Quartet.

The inhabitants of a certain wealthy town think nothing of throwing objects away. However, their waste is priceless to Rudo, a resident of the town's slums. Despite the constant warnings from his adoptive father Regto, Rudo spends his days searching for reusable materials that would otherwise be sent to the giant disposal area known as the Pit. Due to its vastness, the Pit doubles as a means of criminal punishment; those dropped in are never to return again. When Regto is murdered by a mysterious assailant, Rudo is falsely accused of the crime and thrown into the Pit. To his surprise, he awakens in a trash-filled area inhabited by enormous monsters formed from the junk. As the toxic air and Trash Beasts push Rudo to the brink of death, he is saved by Enjin, one of the Cleaners who wield weapons known as Vital Instruments to fight the monstrosities. Having gained his own Vital Instrument, Rudo soon joins the Cleaners in the hopes of finding a way to escape the Pit and avenge his father.

This party doesn't need an incompetent magician who can only use supportive magic. You're fired, Alec Ygret. Suddenly, Alec, a court magician who had joined the crown prince's party to help him conquer dungeons—was banished from the party. And not just the party, but the crown prince's harassment has banished him from the royal palace as well, and a friend from the magic academy approached Alec, who was at his wit's end. Hey, Alec. Do you want to try to conquer the dungeon with us again? And so, together with the friends he used to party with, Alec begins his second journey in life. This is the adventure story of a former court magician who had been abandoned. Four years ago, the Lasting Period, a party of four that had been called legendary, has gradually spread its name around the world. (Source: Kodansha, translated)

Melphiera Marchalrayd, the daughter of a count, dedicates her time to researching the culinary possibilities of monster meat—a peculiar endeavor started by her late mother. By teaching the people of the Marchalrayd lands to prepare such exotic ingredients, Melphiera hopes to help stave off famine. Unfortunately, her unique tastes and intimate knowledge of monsters have led to her social isolation: few nobles interact with her willingly, disdainfully calling her the Voracious Villainess. When a monster attack erupts at a royal banquet—where Melphiera has been sent to find a husband—Aristide Rogier du Galbraith, the younger brother of the crown prince, leaps to her aid. Due to his terrifying skill in slaying monsters, Aristide has earned the title of Blood-Man Duke. Charmed by Melphiera's fearlessness and intriguing culinary prowess, Aristide soon declares his intent to propose. Together, Melphiera and Aristide, high society's most eccentric couple, strive to see beyond the cruel rumors and encourage each other's fascination with monsters and the art of preparing them.