  This paper describes a novel idea of a fine-grained fully-active plastic
scintillator detector made of many optically independent
$1\times1\times1~\text{cm}^3$ cubes with readout on three orthogonal
projections by wavelength shifting fibers. The original purpose of this
detector is to serve as an active neutrino target for the detection,
measurement and identification of the final state particles down to a few
tenths MeV kinetic energies. The three readout views as well as the fine
granularity ensure powerful localization and measurement of the deposited
energy combined with good timing properties and isotropic acceptance. The
possible application as a new active target for the T2K near detector, initial
simulation studies and R&D test results are reported.
