  The chirality of chiral multifold fermions in reciprocal space is related to
the chirality of the crystal lattice structure in real space. In this work, we
propose a strategy to detect and identify opposite-chirality multifold fermions
in nonmagnetic systems by means of second-order optical transports. The chiral
crystals are related by an inversion operation and cannot overlap with each
other by any experimental operation, and the chiral multifold fermions in the
crystals host opposite chiralities for a given k-point. A change of chirality
is indicated by a sign change of the second-order charge current dominated by
chiral fermions. This strategy is effective to study the relationship between
chiralities in reciprocal and real spaces by utilizing bulk transport.
