adverb, adverb taking the 'to' particle
sound of a ghost appearing
Onomatopoeic phrase evoking a spooky, eerie atmosphere, often used in manga, anime, or ghost stories when a ghost or yōkai appears.
お化けが出るとき、ヒュードロドロという音がした。
When the ghost appeared, there was a spooky 'hyuu-dorodoro' sound.
Compound of the onomatopoeic elements ヒュー (a whistling or howling sound) and ドロドロ (a thick, eerie, or muddy sound), mimicking the classic spooky noise associated with ghost appearances in Japanese popular culture.