Watch Da Birdie
I buy cakes for myself on my birthday it's not weird lots of people do it I bet
Recon this anime is geared for older audiences?
Probably not beyond simply representing a game they grew up with.
It's airing in the same timeslot as the normal Anime, bar on Wednesday instead of Thursday, so there's not going to be a notable jump in how "dark" or "adult" it is, which wouldn't make sense anyway since it's based on a kid's game.