I'd been reading Oshi no Ko in manga form, but I let my guard down—I had no idea it would become such a dominant anime.
I'd finished reading the original up to around the end of the second arc (I think), but for the sake of writing this I watched the first episode, and yeah, it makes total sense that it became a smash hit.

The original is by Aka Akasaka, known for 'Kaguya-sama: Love Is War.' The art is by Mengo Yokoyari, known for works like 'Scum's Wish.' Apparently Aka Akasaka is male and Mengo Yokoyari is female.
Akasaka worked on this series concurrently with 'Kaguya-sama: Love Is War,' and both became huge hits. He's said he amassed an enormous fortune.

Now, the all-important synopsis goes something like this. Goro, an obstetrician/gynecologist in the countryside, had become an idol otaku thanks to the influence of Sarina, a girl who was attached to him as a patient and who died at the tender age of 12. Then his favorite idol, Ai Hoshino—who was on hiatus—shows up at his clinic, pregnant with twins. Renewed in his admiration for Ai, who refuses to give up either having her children or her idol career, Goro decides to wholeheartedly support her secret birth and attends to her as her doctor. But on the day Ai gives birth, Goro is murdered by Ryosuke, Ai's stalker.
Goro is reborn as Ai's child, Aquamarine Hoshino (Aqua). Aqua's twin sister, Ruby Hoshino, is Sarina reincarnated. The two realize they both retain memories from their previous lives, but don't go so far as to realize they were once doctor and patient. And so the two grow up under Ai, cheering her on as she resumes her idol career while keeping her childbirth a secret. (Partially excerpted from Wikipedia.)

After that, there's a dramatic turn of events, and the anime's first episode ends right where the first volume of the manga does—and man, the buildup to this point is brilliantly crafted.
It's no wonder it swept various manga awards. If anyone out there hasn't seen it, it's not too late, so please watch the anime from episode one.

Now, as for the score this time, it nestles in alongside the show without ever overstepping, and in a good way, it doesn't leave that strong an impression. Since the character songs sung by the idols are the main draw, I think they deliberately built it this way—and I'd say that's a clever strategy.

The composer is Takuro Iga. He's worked on all sorts of titles like 'Magical Girl Raising Project,' 'Fuuka,' 'Case File n°221: Kabukicho,' and 'Asteroid in Love.'

Let's look at some of the more memorable cues.

The one you simply can't leave out is 'Ai1.' It's the striking theme for Ai Hoshino—a legendary idol who, having met her own children born from nothing but lies, comes to know kindness.

https://www.youtube.com/watch?v=hLrs4V4BYEw&list=OLAK5uy_m6IjVl0gHGex8ugCT0AC9rzrijEZ6Y7mA&index=2



'Mother and Children' is another one you can't skip. Setting the heartfelt connection—and the tragedy—between Goro and Sarina, reborn as Ai's children, and their mother Ai Hoshino to melody, this song is a masterpiece no matter what anyone says.

https://www.youtube.com/watch?v=APg1UZR1h6w&list=OLAK5uy_m6IjVl0gHGex8ugCT0AC9rzrijEZ6Y7mA&index=24



To close, let's part ways while watching the PV for the second season, which is currently airing.

https://www.youtube.com/watch?v=GKvBR7tR-Kk
Oshi no Ko

Quoted from the official site https://ichigoproduction.com/