The man who Hallow called as Willow to his time to turn his face and show his new look toward Hallow. In the world of the mortals, dead, and throughout the road to the purgatory, most reapers are not aware of other reaper's appearance. But once in the past, Hallow had quite a history with the reaper in front of him which why with only a single glance, he immediately knows who it was.
"Don't call me Willow. That name sounds so lame," Willow said with a look of disappointment.