The episode bundled with the 13th volume is about the Sumo competition that held at Tempest for the first time, suggested by Rimuru. The three-part OVA bundled with the 14th, 15th, and 16th manga volumes is an original trilogy written by Fuse. Rimuru has been teaching Shizue's students at Ingracia Kingdom's Freedom Academy. The time has come for the school's annual outdoor training event, where the students will test their combat skills in the field. Rimuru is determined to win the competition and take home the prize money, but he is challenged by Jeff, an honorary teacher who sees Rimuru as a rival. The competition is underway when suddenly an unexpected enemy appears! (Source: MAL News & ANN)

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. [Written by MAL Rewrite]

Following the events of "Scorched Halloween," the world is introduced to a terrifyingly powerful Strategic class magician. In an effort to uncover the identity of this person, the United States of the North American Continent (USNA) dispatches the most powerful asset in its arsenal to Japan on a covert mission—the elite magician unit "Stars" and its commander, Angie Sirius. At First High School, Tatsuya Shiba and his friends are having a farewell party for Shizuku Kitayama, who is leaving to study abroad in the USNA as part of an exchange program. In her place, the group welcomes the beautiful Angelina "Lina" Kudou Shields. Around the same time, Tatsuya is informed about the USNA's plan to uncover his true identity. Elsewhere in Tokyo, numerous reports arise of seemingly random bodies found drained of blood. Dubbed as the works of a vampire, it does not take long for Tatsuya to connect the dots and realize that it is almost impossible for the timing of these events to be mere coincidences. [Written by MAL Rewrite]

The episode bundled with the 13th volume is about the Sumo competition that held at Tempest for the first time, suggested by Rimuru. The three-part OVA bundled with the 14th, 15th, and 16th manga volumes is an original trilogy written by Fuse. Rimuru has been teaching Shizue's students at Ingracia Kingdom's Freedom Academy. The time has come for the school's annual outdoor training event, where the students will test their combat skills in the field. Rimuru is determined to win the competition and take home the prize money, but he is challenged by Jeff, an honorary teacher who sees Rimuru as a rival. The competition is underway when suddenly an unexpected enemy appears! (Source: MAL News & ANN)