Comic Girls is a four-panel manga by Kaori Hanzawa, which began serialization in Houbunsha’s seinen manga magazine Manga Time Kirara Max from May 2014. An anime adaptation by Nexus aired between April and June 2018.
The song, トライアングル (Triangle) is sang by Illumination STARS, one of the 6 units appearing on the game THE iDOLM@STER: Shiny Colors.
Both the music and the anime didn’t belong to me.