Since they eat metal and expel nightmares, Banya brought the blue-colored male Bulgasari (called Chul) to the house, thinking that So-Yoon's Grandmother was having nightmares (but it was really back pain from helping carry three of So-Yoon's fellow students off the mountain). The lilac-colored female Bulgasari (called Suhl) couldn't find her husband afterwards, so she followed So-Yoon down the mountain (who had forgotten her Rosary) and was nearly stepped on by several people, making Suhl angry, causing her to go on a metal-eating rampage. Banya noticed that Suhl had gone to So-Yoon's school and came and stopped her (since she lost control of herself), turning her back into her original size.Later, since So-Yoon was left vulnerable without her Rosary therefore allowing an evil spirit to possess her, Banya threw Chul at her. Chul was then able to expel the evil spirits (after being encouraged by So-Yoon since she said he was "very trustworthy") allowing Banya send the spirit to the afterlife. Ajussi is the one who named them (which Banya said the Ajussi had "horrible naming sense"). So-Yoon's Rosary is strung together using the Bulgasari's tail hair and is vulnerable to fire.
According to Goong-Bi, a Bulgasari is a sacred being that chased away nightmares and evil spirits from dreams. It can also bring one's subconscious to the surface. This ability enabled So-Yoon to summon Bub-Woon from inside her.
- Banya was surprised that So-Yoon could see Chul.
- The female bulgasari are striped on their backs.
- Bulgasari can also mean "starfish" in Korean, so when Banya is telling So-Yoon what Bulgasari are, she thought he was talking about starfishes.
- Because of Suhl's rampage, Hope Middle School had to temporarily be closed down.