As seen in Volume 8 of Dengeki G's Love Live! Days
Dia is eating at Sakanaya-Senbonichi, a real seafood restaurant in Numazu (101 Senbon Minatomachi 3F Senbonichi Bldg., Numazu 410-0845 Shizuoka Prefecture). They advertise that the staff does not speak English but do have an English menu.