Seen is a captured image from a promotional video for author Kim Su-ji's web fiction "Under the Oak Tree" serviced on the local e-book platform operator RIDI. Captured from RIDI's YouTube channel

The Korean web fiction "Under the Oak Tree" has made its way onto The New York Times' (NYT) Best Sellers list, setting a milestone for Korea's rapidly growing digital literature industry.

The romance-fantasy written by author Kim Su-ji debuted at No. 7 on the Hardcover Fiction section of the U.S. newspaper's list released on Nov. 13, RIDI, a local e-book platform behind the novel, announced Thursday.

This marks the first time a hardcover edition of a Korean web fiction story has been featured on the list, often regarded as the most influential ranking of bestselling books in the United States.

Published on RIDI from 2017 to 2022, "Under the Oak Tree" captivated readers with its detailed storytelling, complex characters and richly developed medieval fantasy setting.

English hardcover edition of novel "Under the Oak Tree" / Courtesy of Penguin Random House

Set in a fictional medieval world, "Under the Oak Tree" tells the story of Maximilian, a duke's shy and insecure daughter who struggles with a speech impediment, and Riftan Calypse, a knight of humble origins.

Forced into an arranged marriage, the two face separation when Riftan leaves for a military campaign shortly after their wedding night. When he returns three years later as a celebrated hero, their love story unfolds.

Unlike many romance-fantasy web novels with perfect protagonists, "Under the Oak Tree" shines by portraying flawed and relatable characters, such as the vulnerable and growing Maximilian and the persevering and accepting Riftan.

The author spent years refining the story before its debut. Originally conceived while she was in university, Kim dedicated six years to revising and completing the plot before launching the serialized web novel in January 2017. Over five years, the author published the two-volume novel, totaling 450 chapters.

The series garnered immense popularity on RIDI's platform, eventually being adapted into a webtoon, or online comic, and translated into multiple languages. The English e-book version has been a particular success, achieving bestseller status on Amazon in several countries, including the U.S., France and Mexico, and leading to a publishing deal with Penguin Random House, one of the world's largest publishers, in July 2023.

The hardcover English edition, published on Nov. 5, climbed up the chart in just its first week of release, indicating its widespread appeal. The book's early momentum suggests the potential for it to rise in the rankings in the following weeks.

Seen is a limited edition hardcover of the romance fantasy novel "Under the Oak Tree" by author Kim Su-ji. Courtesy of RIDI

Its journey from a popular online series to a global literary phenomenon also demonstrates the growing international appeal of Korean web novels, which have traditionally been overshadowed by the global prominence of other genres such as K-dramas, K-pop and cinema. With its NYT Best Seller debut, "Under the Oak Tree" has set a new benchmark for the global reach of Korean web novels.

RIDI emphasized the significance of this feat, noting the success of this novel demonstrates the global competitiveness of Korean web fiction.

"The global popularity of 'Under the Oak Tree' has reaffirmed our belief in the universal appeal of great storytelling," a RIDI official said. "We will continue our partnership with Penguin Random House to produce more compelling content."

Beyond the novel itself, the webtoon adaptation also garnered widespread acclaim. It became a bestseller in Japan, achieving over 10 billion won ($7.14 million) in sales within just six months of its release in July. The Japanese edition of the webtoon's print version saw massive demand, requiring a second print run just one day after its release.

In the U.S., the webtoon version dominated Amazon's Best Sellers in Romance Graphic Novels section and USA Today's Best-selling Booklist.