The author of oshi no ko explains the story that inspired him for the opening song of the anime 

The official Twitter account for Aka Akasaka and Mengo Yokoyari's Oshi no Ko manga revealed a new short story by Akasaka on Wednesday titled "45510." The short story served as the basis for YOASOBI's opening theme song "Idol" for the manga's television anime adaptation, and looks at the story's idol Ai from a different perspective. 

The anime premiered in Japan on Wednesday with a 90-minute first episode. HIDIVE is streaming the anime as it airs in Japan. The 90-minute version first episode also played in advance screenings at cinemas nationwide in Japan on March 17. 

Plot: Gorou is a gynecologist and idol fan who's in shock after his favorite star, Ai, announces an impromptu hiatus. Little does Gorou realize that he's about to forge a bond with her that defies all common sense! Lies are an idol's greatest weapon in this outrageous manga from Aka Akasaka (Kaguya-sama: Love is War) and Mengo Yokoyari (Scum's Wish). 

Queen Bee performs the ending theme song "Mephisto." 

Source: Twitter page ufficial, Anime News Network