JYJ's "Music Essay" has become Kyobo's weekly bestseller! The largest book retailer in Korea states that an overwhelming majority of JYJ's "Music Essay" sales were from women in their 20's and 30's. To be more precise, Kyobo cited that 95% of its sales were from this group. On their site, they accredit JYJ's success to their enormous fan base and their participation in various activities. "Due to the members fandom and activities in dramas and musicals, their popularity can be seen by the huge amount of interest in them by the people in their 20's and 30's." Congratulations to JYJ! Thanks to Cindy for the tip.