Vicious Ravens are found in the upper half of the first section of Arqa Block in Tartarus. The will later appear in the second half of Malebolge within the Abyss of Time.
Persona 4
Vicious Ravens appear in Halls 5 and 6 of the Steamy Bathhouse in the Midnight Channel. These Shadows may drop the Karma Lamp material when defeated. Selling 6 Karma Lamps at Daidara will unlock the Battle Camisole female armor in the shop's inventory.
Persona 4 Golden
Vicious Raven appears in Halls 3 to 10 of the Steamy Bathhouse within the Midnight Channel. Upon defeat they may drop Blue Quartz as well as items listed above.