  We present the results of study of the Galactic candidate luminous blue
variable Wray 15-906, revealed via detection of its infrared circumstellar
shell (of \approx2 pc in diameter) with the Wide-field Infrared Survey Explorer
and the Herschel Space Observatory. Using the stellar atmosphere code CMFGEN
and the Gaia parallax, we found that Wray 15-906 is a relatively
low-luminosity, log(L/Lsun)\approx5.4, star of temperature of 25\pm2 kK, with a
mass-loss rate of \approx3\times10^{-5} Msun/yr, a wind velocity of 280\pm50
km/s, and a surface helium abundance of 65\pm2 per cent (by mass). In the
framework of single star evolution, the obtained results suggest that Wray
15-906 is a post-red supergiant star with initial mass of \approx26\pm2 Msun
and that before exploding as a supernova it could transform for a short time
into a WN11h star. Our spectroscopic monitoring with the Southern African Large
Telescope (SALT) does not reveal significant changes in the spectrum of Wray
15-906 during the last 8 yr, while the V-band light curve of this star over
years 1999--2019 shows quasi-periodic variability with a period of \approx1700
d and an amplitude of \approx0.1 mag. We estimated the mass of the shell to be
2.9\pm0.5 Msun assuming the gas-to-dust mass ratio of 200. The presence of such
a shell indicates that Wray 15-906 has suffered substantial mass loss in the
recent past. We found that the open star cluster C1128-631 could be the birth
place of Wray 15-906 provided that this star is a rejuvenated product of binary
evolution (a blue straggler).
