Just to prevent future confusion since the manga doesn't tell you:
Yamashiro's other friend we see in ch. 10 is not Erika. I've seen some people make that assumption. Nobody named Erika has appeared in the manga so far. You don't actually learn her whole name until well into volume 3, so for now you can just call her by her nickname Piyo.
last edited at Jul 1, 2020 6:38PM