In celebration of Halloween Day in 2017, Lotte C&T collaborated with global character brand Line Friends and world-renowned artist Crack & Cal to present Hi Spirts! Line Friends x Craig&Karl (hello Halloween!) was planned. Hello Halloween!, which was held from October 3rd to October 31st, 2017 in the Lotte World Tower area, is a one-off Halloween Day event that has been organized as a festival for the longest period and largest scale ever. With Crack & Cal's sensuous touch, Line Friends' characters Brown and Sally were reborn as 12-meter-tall giant balloons, and a total of 22 works, including 20 sculptures designed by the artist, will be displayed around the Lotte World Tower. ​Sculptures wearing Halloween costumes welcome visitors in a friendly way, just like the title of the project, Hello! The witty-looking sculptures contain the artist's message of sharing meaningful moments with family, friends, and acquaintances with a positive attitude toward life. After sunset, the lights installed inside the sculpture turn on, creating a mysterious atmosphere for the balloon pieces. ​In addition to the exhibition, there are various events that families, friends, and lovers can enjoy together during the period. Crack & Cal is a designer duo that has collaborated with multinational companies such as Louis Vuitton, Kiehl's, Nike, Apple, and Sephora, and is based in New York, USA and London, England.