Over the past decades, a stream of research has witnessed that the changing sociopolitical and socioeconomic dynamics between North Korea and the outside world have triggered socioeducational changes in North Korea. Due to Kim Jong-un’s political conviction in ‘education’—with its heavy emphasis in the English language—as ‘the mother of science and technology,’ in recent years, such endeavors have become further accelerated in a structured and pragmatic manner. To date, a rising number of corpus-based studies have attempted to delineate the textual and formatting differences between English textbooks produced by Kim Jung-un’s regime and those produced by his predecessors, but not to explain how the English language input was implemented to reflect educational reform. In order to augment prior findings, therefore, the present study aims to investigate the shift in language input manifested in North Korean English textbooks, both quantity- and quality-wise. The results revealed that the textbook revisions made in the Kim Jong-un era were found to satisfy the lexical threshold (95%) of the BNC/COCA 3K core vocabulary, implying that the revised versions were thoroughly controlled with the optimum amount of language input. Regarding language input quality, Kim Jong-un’s revised textbooks held a larger portion of authentic and high-frequency 3-gram lexical bundles, which can generally be observable across the COCA, than those in the Kim Jong-il era. Based on the quantitative and qualitative enhancement of language input, implications are discussed in association with the concept of self-independence and maintenance of the Kim Jong-un regime.