  This document presents the measurement of $B^0$ meson lifetimes using the
2019 Belle II dataset that corresponds to an integrated luminosity of $8.7 \pm
0.2$ fb$^{-1}$. Each candidate is fully reconstructed with hadronic decay final
states on the signal side, while the rest-of-event technique allows to infer
the decay vertex position on the other (tag) side. $B^0$ lifetime is extracted
from an unbinned maximum likelihood fit to the distribution of the difference
between the signal side $B^0$ candidate and the tag side decay times. The
measured lifetime is $\tau_{B^0} = 1.48 \pm 0.28 \pm 0.06 $ ps, where the first
uncertainty is statistical and the second is systematic.
