  Mechanism of simultaneous non-sequential four-neutron ($4n$) emission (or
`true' $4n$-decay) has been considered in phenomenological five-body approach.
This approach is analogous to the model of the direct decay to the continuum
often applied to $2n$- and $2p$-decays. It is demonstrated that $4n$-decay
fragments should have specific energy and angular correlations reflecting
strong spatial correlations of `valence' nucleons orbiting in their
$4n$-precursors. Due to the Pauli exclusion principle, the valence neutrons are
pushed to the symmetry-allowed configurations in the $4n$-precursor structure,
which causes a `Pauli focusing' effect. Prospects of the observation of the
Pauli focusing have been considered for the $4n$-precursors $^7$H and $^{28}$O.
Fingerprints of their nuclear structure or/and decay dynamics are predicted.
