The official website for the Yatogame-chan Kansatsu Nikki anime announced today that the fourth season of the adaptation will premiere on TV Aichi on April 2nd .
However, the first episode will be a "special announcement," so the actual first episode of the anime will air in the second week.
In addition to TV Aichi, the season will air on BS11 and AT-X.
The first three seasons will have marathon screenings on the AT-X channel on March 30th, March 31st, and April 1st.
Source: ANN
