Unidentified oni

An oni was responsible for a series of missing children incidents in Westruun in an adventure hook called The Stuff of Nightmares in the Tal'Dorei Campaign Setting sourcebook, set in 812 PD.

Description
This oni was sadistic and clever at covering their tracks.

History
In addition to the series of missing children incidents, the oni was responsible for a plague of nightmares affecting people of all ages. Magical experts were sought to look into either matter, although the oni was able to cover their tracks well. It's unclear whether the nightmares were also connected to the dream-reading stall recently opened by tiefling twins Nyx and Vryll.

Character information
The character is identified only as an oni, the typical version of which is described in the Monster Manual, p. 239, or in the Basic Rules, p. 336.