Boogieman Under the Couch

Yeonseok, the head of a household, suffers from insomnia. The cause of his insomnia is the monster under the couch. People around him laugh, dismissing it as a nightmare that only children would fear. Even Yeonseok is unsure whether the monster is real or just a figment of his imagination. Then one day, Yeonseok comes face to face with the monster under the couch.