  We report the mass measurements of neutron-rich isotopes produced via
spontaneous fission of ${}^{252}$Cf using a multi-reflection time-of-flight
mass spectrograph. The mass of ${}^{155}$Ce is determined experimentally for
the first time. A discrepancy between the experimental and literature values
was found for the mass of ${}^{127}$Sb, which was previously deduced through
indirect measurements. In comparison with several theoretical predictions, both
the values and the trend of the mass excesses of ${}^{152-155}$Ce cannot be
consistently explained. The wide-range and simultaneous mass measurements of
the multi-reflection time-of-flight mass spectrograph enable us to reexamine
existing mass data. The new measurements suggest corrections to the present
values, including data from previous Penning trap mass measurements.
