Después de tres años de matrimonio, Wendy Stewart estaba acostumbrada a los comentarios sarcásticos de Michael Lucas, sus amenazas frecuentes sobre el divorcio e incluso su indulgencia con una amante. Pensó que podría soportar todo esto toda su vida, hasta que accidentalmente quedó embarazada de un niño que Michael no quería. Finalmente desesperada, Wendy firmó el acuerdo de divorcio y se fue. Pensó que podrían haberse separado para siempre, pero Michael se negó a dejar de buscarla después del divorcio. Cuando se encontraron de nuevo, ella era la mejor diseñadora del mundo. Sonriendo dulcemente a su exmarido, dijo: —Mi querido, ya estamos divorciados. Michael simplemente la miró fríamente: —Dime, ¿qué hará falta para que nos reconciliemos?
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.