Choi Leah at the local branch of the company said those who booked hotels in May are likely to be tourists planning on taking an early vacation in June.

The "staycation" trend -- spending summer vacation at urban hotels instead of long-distance travel during the sweltering heat wave -- contributed to the capital city taking second place, Choi said.

Busan and Osaka followed with 6.1 percent and 5.5 percent, respectively, while Tokyo and Fukuoka both received 3.7 percent, according to the data.

"Due to the onset of summer weather and the increase in the number of people who try to avoid the peak season, more and more people are taking early vacations," Choi said. (Yonhap)