Did my memory is bad or the Tarumi girl is the one friend from Shimamura's childhood ? Either i think it's the disturbance the horoscope was talking about.
Edit : Wait does the manga had the flashback about her already and i'mtoo dumbto remember or does it's the first time she is mention ?
Shimamura's just completely given up questioning Yashiro's existence, huh? I love how she just has a whole category of unfamiliar behaviours she's labelled "Adachi-like".