  We propose a new Universal Extra Dimensional model that is defined on a
six-dimensional spacetime which has a two-sphere orbifold $S^2/Z_2$ as an
extra-space. We specify our model by choosing the gauge symmetry as
SU(3)$\timesSU(2)\timesU(1)_Y \timesU(1)_X$, introducing field contents in
six-dimensions as their zero modes correspond to the Standard model particles,
and determining a boundary condition of these fields on orbifold $S^2/Z_2$. A
background gauge field that belongs to U(1)$_X$ is introduced there, which is
necessary to obtain massless chiral fermions in four-dimensional spacetime. We
then analyze Kaluza-Klein(KK) mode expansion of the fields in our model and
derive the mass spectrum of the KK particles. We find that the lightest KK
particles are the 1st KK particle of massless gauge bosons at tree level. We
also discuss the KK parity of the KK modes in our model and confirm the
stability of the lightest KK particle which is important for dark matter
physics.
