Chapter fifty-four’s title image is from “Futsuu” by CRYAMY
Chapter fifty-five’s is from “Fukkatsu no Jumon” by sumika
On page 41, they visit the Shibuya branch of Ishibashi. (I’m pretty sure that guitar-man-was-not-meant-to-know in the seventh panel is entirely fictional. Not gonna risk researching it in case my computer turns into a portal to the underworld. That said, it does kinda resemble an electric version of the Pikasso guitar.)
Page 43, they’re now at Cafe Flamingo, though according to Google it’s permanently closed. Page 44, the mentions of Tochigi and gyoza probably means they’re in Utsunomiya somewhere, but I couldn’t nail it down further with any specificity. There’s a few Hard Offs (Hards Off?) in Utsunomiya - like this one. And then the next page just straight-up says it’s Utsunomiya. I’ve really gotta learn to read the whole chapter before I start making notes…
Page 51, the manga that Nijika is holding is the first volume of Shojo Tsubaki.
Page 54, I honestly preferred Nijika’s original cover drawing better.
Page 55, I probably don’t need to point out that they’re playing Splatoon… or (presumably) one of the sequels.