The BL novel Yes Ka No Ka Hanbun Ka was turned into an anime movie for BL Fes in December 2020 and the theme song single is available for purchase and download. The theme song is titled Sekai to Kakurenbo 世界とかくれんぼ (Hide and Seek with the World) and is sung by the voice cast of the two main characters Abe Atsushi 阿部敦 (Kunieda Kei) and Kawahara Yoshihisa 川原慶久 (Tsuzuki Ushio). The single comes with three songs: the theme song, the theme song sung by Abe Atsushi, and the theme song sung by Kawahara Yoshihisa. It’s a pretty catchy song and the lyrics were written by the novel author so it fits the movie perfectly. I am glad they kept the main voice cast from the drama CD because they were perfect. I hate it when you get used to a cast and they change it on you.
Get the single here: https://orcd.co/sekai_to_kakurenbo
You can watch the movie on Crunchyroll.