  Streamers bring gas from outer regions to protostellar systems and could
change the chemical composition around protostars and protoplanetary disks. We
have carried out mapping observations of carbon-chain species (HC$_3$N,
HC$_5$N, CCH, and CCS) in the 3mm and 7mm bands toward the streamer flowing to
the Class 0 young stellar object (YSO) Per-emb-2 with the Nobeyama 45m radio
telescope. A region with a diameter of $\sim0.04$ pc is located north with a
distance of $\sim 20,500$ au from the YSO. The streamer connects to this north
region which is the origin of the streamer. The reservoir has high density and
low temperature ($n_{\rm {H}_2} \approx 1.9 \times 10^4$ cm$^{-3}$, $T_{\rm
{kin}} = 10$ K), which are similar to those of early stage starless cores. By
comparisons with the observed abundance ratios of CCS/HC$_3$N to the chemical
simulations, the reservoir and streamer are found to be chemically young. The
total mass available for the streamer is derived to be $24-34$ M$_{\odot}$. If
all of the gas in the reservoir will accrete onto the Per-emb-2 protostellar
system, the lifetime of the streamer has been estimated at ($1.1 -
3.2$)$\times10^{5}$ yr, suggesting that the mass accretion via the streamer
would continue until the end of the Class I stage.
