  Recently, there has been a growing interest in investigating homogeneous but
anisotropic spacetimes owing to their relation with nonrotating, uncharged
black hole interiors. We present a description of axial perturbations for a
massless scalar field minimally coupled to this geometry. We truncate the
action at the quadratic perturbative order and tailor our analysis to compact
spatial sections. Perturbations are described in terms of perturbative gauge
invariants, linear perturbative constraints, and their canonically conjugate
variables. The entire set, encompassing perturbations and homogeneous degrees
of freedom, is consolidated into a canonical one. We employ a hybrid approach
to quantize this system, integrating a quantum representation of the
homogeneous sector using Loop Quantum Cosmology techniques with a conventional
field quantization of the perturbations.
