The shop he meant was the Kurosewa Instruments shop inside the Modi department store vis-à-vis from Machida Station, which was renamed Shirosawa Instruments in the anime.
Things are more complicated back at Machida Station, where Mafuyu has several run-ins with Hiiragi.
The goal of that little stroll through the neighborhood was, of course, Kamakura’s Yuigahama Beach, which is a popular date spot.