Story
Living alone and never having had a girlfriend, 37-year-old Satoru Mikami is dissatisfied with how his life has turned out. But after dying at the hands of a robber, he awakens to a fresh start in a new world...as a slime monster. (Source: Yen Press) Note: Includes 61 extra chapters.
Synopsis via AniList (English).
Preview
From the anime adaptation: That Time I Got Reincarnated as a Slime.