  The formation scenario of brown dwarfs is still unclear because observational
studies to investigate its initial condition are quite limited. Our systematic
survey of nearby low-mass star-forming regions using the Atacama Compact Array
(aka Morita array) and the IRAM 30 m telescope in 1.2 mm continuum has
identified a centrally concentrated starless condensation with a central H$_2$
volume density of $\sim$10$^6$ cm$^{-3}$, MC5-N, connected to a narrow (width
$\sim$0.03 pc) filamentary cloud in the Taurus L1495 region. The mass of the
core is $\sim$0.2-0.4 $M_{\odot}$, which is an order of magnitude smaller than
typical low-mass prestellar cores. Taking into account a typical core to star
formation efficiency for prestellar cores ($\sim$20%-40%) in nearby molecular
clouds, brown dwarf(s) or very low-mass star(s) may be going to be formed in
this core. We have found possible substructures at the high-density portion of
the core, although much higher angular resolution observation is needed to
clearly confirm them. The subsequent N$_2$H$^+$ and N$_2$D$^+$ observations
using the Nobeyama 45 m telescope have confirmed the high-deuterium
fractionation ($\sim$30%). These dynamically and chemically evolved features
indicate that this core is on the verge of proto-brown dwarf or very low-mass
star formation and is an ideal source to investigate the initial conditions of
such low-mass objects via gravitational collapse and/or fragmentation of the
filamentary cloud complex.
