  MAXI J1421-613 is an X-ray burster discovered by Monitor of All-sky X-ray
Image (MAXI) on 9 January 2014 and is considered to be a low-mass X-ray binary.
A previous study analyzing follow-up observation data obtained by Suzaku on 31
January to 3 February 2014 reported that an annular emission of ~3'-9' radius
was found around the transient source. The most plausible origin of the annular
emission is a dust scattering echo by the outburst of MAXI J1421-613. In this
paper, we confirm the annular emission by analyzing the data of the Swift
follow-up observation which was conducted by the photon counting mode on 18
January 2014. In a radial profile, we found an annular emission at ~2'.5-4'.5.
Its spectrum was well explained by an absorbed power law, and the photon index
was higher than that of MAXI J1421-613 itself by delta Gamma~2. The flux and
radius of the annular emission observed by Swift are explained by dust
scattering of the same outburst as is responsible for the annular emission
observed by Suzaku. Assuming that the dust layer causing the annular emission
found by Swift is located at the same position as the CO cloud in front of MAXI
J1421-613, the distance to the transient source was estimated to be ~3 kpc,
which is consistent with the value estimated by the previous study of Suzaku.
