Part IV covers volumes 29 to 47 of the manga and takes place in the year 1999 in the town of Morioh, Japan. The series focuses on Josuke Higashikata, Joseph's son from a Japanese woman, and the Stand users popping in Morioh thanks to the Stand Arrow and how a series of homicides connect to it.
The series is set to premiere in April 2nd on Tokyo MX in Japan. The series will be streamed on Crunchyroll and Viz for overseas markets.
[via Anime News Network]