「人間(にんげん)との一日に三度の鐘の約束が守られている限り動けない」という縛り(しばり)があるから

Meanwhile, Princess Shirayuki, the daughter of the dragon god sealed at the bottom of Demon Pond, eagerly desired every day: 'I want to leap out of the mountain quickly to go to my beloved lover.' However, she was bound by the severity of the promise: 'As long as the promise with humans that the bell rings three times a day is kept, I cannot leave this pond.' The absolute power of 'words and promises' that bind even the spirits of nature is portrayed.