  Pair-instability supernovae (PISNe) are explosions of very massive stars that
may have played a critical role in the chemical evolution and reionization of
the early Universe. In order to quantify their roles, it is required to know
the PISN event rate at z > 6. Although Roman Space Telescope has a capability
to discover PISNe at z > 6, identifying rare high-redshift PISN candidates
among many other transients is challenging. In order to efficiently identify
PISN candidates at z > 6, we propose to add sparse F213 observations reaching
26.5 mag (or deeper) every half year in the High Latitude Time Domain Survey.
By adding the F213 information, PISNe at z > 6 can be efficiently identified in
the color-magnitude diagram.
