It shows it in the third section for me.
Started chapter 6 b-side, shit's getting real.
Bit curious, which version are you playing it on? It was appearing in the second section for me too (switch version), and still does after getting it.
Yeah, I'm playing the Switch version and the cassette icon is on the second section.
I just managed to complete the Bsides for the first world, 406 deaths. This game will take me all of 2018.
Also, looking at the chapter select, it looks like there is an empty spot to the left of the hearts. Without spoiling me, am I missing some secret thing?