Manga

That Time I Got Reincarnated as a Slime (転生したらスライムだった件) is a manga adaptation based on the light novels of the same name. In addition to the main story, there are also side-story and spin-off manga based on the series.

Main
The main manga is illustrated by Taiki Kawakami and debuted in Kodansha's shōnen manga magazine Monthly Shōnen Sirius on March 26, 2015. Kodansha USA announced their license to the manga during their panel at New York Comic Con on October 6, 2016. The manga essentially follows story from the light novels.

Chapters Not Yet In a Volume

 * 53: Myulan the Witch
 * 54: A Prelude to Catastrophe
 * 55: The Natural Enemy of Monsters
 * 56: Intertwining Thoughts
 * 57: Malicious Visitors

Reincarnated Slime Diary
Slime Diary: That Time I Got Reincarnated as a Slime (転スラ日記 転生したらスライムだった件), often shortened to Reincarnated Slime Diary (転スラ日記), is a 4-koma spin-off manga based on the main series.

Trivia

 * Out of the various manga adaptations, four are currently released on Monthly Shōnen Sirius.