The official twitter account of Bishounen Tanteidan revealed the schedule for the anime adaptation.The TV anime is scheduled for 2021.
Pretty Boy Detective Club (美少年) is a Japanese mystery novel series, written by Nisio Isin and illustrated by Kinako. Kodansha released eleven volumes from October 2015 to December 2019 under their Kodansha Taiga label.
A manga adaptation titled Bishōnen Tanteidan (美少年探偵団), with art by Suzuka Oda, began serialization in Kodansha's shōjo manga magazine Aria in April 2016, and it moved to Kodansha's shōnen manga magazine Shōnen Magazine Edge in October 2018 after Aria ceased publication in April 2018, and continued the publication until July 17, 2019. It was collected in five tankōbon volumes. Both the novel series and the manga are licensed in North America by Vertical. An anime television series adaptation by Shaft is scheduled to premiere in 2021.
Source : Official Website