Internationally famous K-pop group BTS released their highly anticipated memoir in South Korea on Sunday, marking their 10-year anniversary.

“Beyond the Story: 10-Year Record of BTS” includes a chronological summary of BTS’ musical career and their plans for future endeavors. The book is 544 pages and is structured like an oral history of the boy band.

Rains prevented many fans from purchasing books Sunday morning, but some still gathered in front of the Kyobo bookstore in Seoul, South Korea.

The book, which is also being released in the United States, quickly reached the top of the Amazon and Barnes and Noble bestseller lists in May just from pre-orders.

The memoir was co-written by members of the band and South Korean journalist Kang Myeong-seok and was published by the U.S.-based Flatiron Books.

The release date of the memoir, July 9, is the day that BTS first began.

“Thank you for saving me when I needed it,” one fan, Audrey, said. She booked a trip to Seoul to coincide with the memoir’s release.

BTS has become a cultural phenomenon, selling out stadiums and dominating charts. The band is estimated to bring around $4.9 billion to South Korea’s economy, or 0.3 percent of the country’s GDP. One in 13 tourists to Korea visit because of BTS.

The band is currently taking a break from touring and releasing new music, as two members complete South Korea’s compulsory military service and others pursue their own projects.

South Korean men must serve a minimum of 18 months in the military. After a debate over whether BTS members should be exempt, Jin, the eldest member, enlisted last year.

His bandmate J-Hope began his service in April.

Before the hiatus, BTS had six No. 1 hits on the Hot 100, and all seven members had solo tracks that made it to the top songs chart.