Thirty-seven-year-old Satoru Mikami is a typical corporate worker, who is perfectly content with his monotonous lifestyle in Tokyo, other than failing to nail down a girlfriend even once throughout his life. In the midst of a casual encounter with his colleague, he falls victim to a random assailant on the streets and is stabbed. However, while succumbing to his injuries, a peculiar voice echoes in his mind, and recites a bunch of commands which the dying man cannot make sense of. When Satoru regains consciousness, he discovers that he has reincarnated as a goop of slime in an unfamiliar realm. In doing so, he acquires newfound skills—notably, the power to devour anything and mimic its appearance and abilities. He then stumbles upon the sealed Catastrophe-level monster Storm Dragon Veldora who had been sealed away for the past 300 years for devastating a town to ashes. Sympathetic to his predicament, Satoru befriends him, promising to assist in destroying the seal. In return, Veldora bestows upon him the name Rimuru Tempest to grant him divine protection. Now, liberated from the mundanities of his past life, Rimuru embarks on a fresh journey with a distinct goal in mind. As he grows accustomed to his new physique, his gooey antics ripple throughout the world, gradually altering his fate.

Death City is home to the famous Death Weapon Meister Academy, a technical academy headed by the Shinigami—Lord Death himself. Its mission: to raise Death Scythes for the Shinigami to wield against the many evils of their fantastical world. These Death Scythes, however, are not made from physical weapons; rather, they are born from human hybrids who have the ability to transform their bodies into Demon Weapons, and only after they have consumed the souls of 99 evil beings and one witch's soul. Soul Eater Evans, a Demon Scythe who only seems to care about what's cool, aims to become a Death Scythe with the help of his straight-laced wielder, or meister, Maka Albarn. The contrasting duo work and study alongside the hot headed Black☆Star and his caring weapon Tsubaki, as well as the Shinigami's own son, Death the Kid, an obsessive-compulsive dual wielder of twin pistols Patty and Liz. Soul Eater follows these students of Shibusen as they take on missions to collect souls and protect the city from the world's threats while working together under the snickering sun to become sounder in mind, body, and soul.

The Abyss—a gaping chasm stretching down into the depths of the earth, filled with mysterious creatures and relics from a time long past. How did it come to be? What lies at the bottom? Countless brave individuals, known as Divers, have sought to solve these mysteries of the Abyss, fearlessly descending into its darkest realms. The best and bravest of the Divers, the White Whistles, are hailed as legends by those who remain on the surface. Riko, daughter of the missing White Whistle Lyza the Annihilator, aspires to become like her mother and explore the furthest reaches of the Abyss. However, just a novice Red Whistle herself, she is only permitted to roam its most upper layer. Even so, Riko has a chance encounter with a mysterious robot with the appearance of an ordinary young boy. She comes to name him Reg, and he has no recollection of the events preceding his discovery. Certain that the technology to create Reg must come from deep within the Abyss, the two decide to venture forth into the chasm to recover his memories and see the bottom of the great pit with their own eyes. However, they know not of the harsh reality that is the true existence of the Abyss.

Taking a break from his time as a teacher, the powerful slime Rimuru Tempest returns to his kingdom, eponymously named Tempest, just in time to begin negotiations with a nearby nation—the Kingdom of Eurazania. While the negotiations are anything but peaceful, they do end successfully, allowing Rimuru to return and finish teaching. When trying to again return to Tempest, this time permanently, Rimuru is stopped by a mysterious figure who is somehow able to constrain the many magical abilities he has at his disposal. In Tempest, the situation is even worse. A group of unknown humans has invaded the land and are assaulting its citizens, both influential and innocent. They are not just trying to bring harm either—they have the intent to kill. Can Rimuru overcome his powerful and dangerous foe and return to Tempest before it is too late?