  The core of neutron-star matter is supposed to be at a much higher density
than the normal nuclear matter density for which various possibilities have
been suggested such as, for example, meson or hyperon condensation and/or
deconfined quark or color-superconducting matter. In this work, we explore the
implication on hadron physics of a dense compact object that has three
"phases", nuclear matter at the outer layer, kaon condensed nuclear matter in
the middle and strange quark matter at the core. Using a drastically simplified
but not unreasonable model, we develop the scenario where the different phases
are smoothly connected with the kaon condensed matter playing a role of
"doorway" to a quark core, the equation of state (EoS) of which with parameters
restricted within the range allowed by nature could be made compatible with the
mass vs. radius constraint given by the 1.97-solar mass object PSR J1614-2230
recently observed.
