  Upgrades to improve the sensitivity of gravitational wave detectors enable
more frequent detections and more precise source parameter estimation. Unlike
other advanced interferometric detectors such as Advanced LIGO and Advanced
Virgo, KAGRA requires different approach for the upgrade since it is the only
detector which employs cryogenic cooling of the test masses. In this paper, we
describe possible KAGRA upgrades with technologies focusing on different
detector bands, and compare the impacts on the detection of compact binary
coalescences. We show that either fivefold improvement in the $100
M_{\odot}$--$100 M_{\odot}$ binary black hole range, a factor of 1.3
improvement in the binary neutron star range, or a factor of 1.7 improvement in
the sky localization of binary neutron stars is well feasible with upgrades
that do not require changes in the existing cryogenic or vacuum infrastructure.
We also show that twofold broadband sensitivity improvement is possible by
applying multiple upgrades to the detector.
