South Korean cryptocurrency exchange Upbit said Friday that nonfungible tokens featuring images of main lead characters from TV drama series “Jirisan” had sold at record-low prices.

NFTs are digital tokens of physical or digital assets, mostly of music or art, that guarantee ownership through blockchain technology.

According to the digital asset trading platform, the pixel art NFTs of the characters played by top Korean actors Gianna Jun and Ju Ji-hoon sold for 18,653 won ($15.50) and 19,916 won last month. Those figures logged the lowest prices among NFTs ever sold within the platform.

“It seems the NFTs were unpopular because the drama series wasn’t as much of a hit as expected,” said an official from the public relations agency representing Upbit.

Despite an all-star cast, the series was criticized for its unnatural computer graphics of Jirisan National Park and excessive product placement, industry sources said. Losing viewers’ interest, its TV ratings mostly remained flat at around 7 and 8 percent, and ended at 9 percent on Dec. 12.

Written by Kim Eun-hee, the star screenwriter behind global hit zombie series “Kingdom” (2019) on Netflix, “Jirisan” tells the story of rangers at the national park going through mysterious accidents on the mountain.