  We report the results of follow-up investigations of a possible new thermally
emitting isolated neutron star (INS), 4XMM J022141.5-735632, using observations
from XMM-Newton and Spectrum Roentgen Gamma (SRG) eROSITA. The analysis is
complemented by Legacy Survey imaging in the optical and near-infrared
wavelengths. The X-ray source, the first to be targeted by XMM-Newton in an
effort to identify new INS candidates from the fourth generation of the
XMM-Newton serendipitous source catalogue Data Release 9 (4XMM-DR9), shows a
remarkably soft energy distribution and a lack of catalogued counterparts; the
very high X-ray-to-optical flux ratio virtually excludes any other
identification than an INS. Within current observational limits, no significant
flux variation nor change of spectral state is registered over nearly ten
years. Future dedicated observations, particularly to search for pulsations,
are crucial to shed further light on the nature of the X-ray source and
relations to other Galactic neutron stars.
