  We discuss the detectability of Warm/Hot Intergalactic medium (WHIM) via the
absorption lines toward bright point sources with a future X-ray satellite
mission, XEUS. While we consider bright QSOs as specific examples, the
methodology can be applied to bright GRB afterglows. We create mock absorption
spectra for bright QSOs (more than 20 QSOs over the all sky) using a light-cone
output of a cosmological hydrodynamic simulation. We assume that WHIM is under
collisional and photo-ionization equilibrium. If WHIM has a constant
metallicity of $Z=0.1Z_\odot$, approximately 2 O{\sc vii} absorption line
system with $>3\sigma$ will be detected on average along a random line-of-sight
toward bright QSOs up to $z=0.3$ for 30 ksec exposure.
