Millie Seojae.

kt millie seojae Co., Ltd. operates Milli's Library, an e-book subscription reading platform in South Korea. It offers audiobooks, chatbooks, object books, and docent books, as well as paper book subscription products. Its products are sold through B2C, B2B, and B2BC channels, serving individual customers, companies, and public institutions. The company was formerly known as Millie Seojae and changed its name to kt millie seojae Co., Ltd. in May 2025; it was founded in 2016 and is headquartered in Seoul, South Korea.