  This study investigates the influence of infection cases of COVID-19 and two
non-compulsory lockdowns on human mobility within the Tokyo metropolitan area.
Using the data of hourly staying population in each 500m$\times$500m cell and
their city-level residency, we show that long-distance trips or trips to
crowded places decrease significantly when infection cases increase. The same
result holds for the two lockdowns, although the second lockdown was less
effective. Hence, Japanese non-compulsory lockdowns influence mobility in a
similar way to the increase in infection cases. This means that they are
accepted as alarm triggers for people who are at risk of contracting COVID-19.
