Korean and Japanese is sister language basically based on the same Chinese character words. Through extensive interactions in various fields for a long time, the two countries have many similarities in terms of language much more than any other country in the world. Of course, Korea has "Hangul", while Japan has "Kana" as own characters, but they are phonetic characters. More than 80% of Korean and more than 90% of Japanese language derive from Chinese characters words. Surprisingly, 2/3 of the two language share exactly same Chinese character words. That means, if one knows basic educational Chinese characters, one can understand the other language and can communicate easily if only know how to pronounce equivalent words.
This book lists 3,754 core Korean words with Japanese equivalents including romanized pronunciation. Main entries are in Hangul (Korean alphabet) alphabetically with Chinese characters, if any, followed by romanized Korean pronunciation. Next, in the same line, the entry’s Japanese equivalents followed by romanized Japanese pronunciation.