hicross.jp/vocabulary/theme/yojijukugo
A free vocabulary database of 38 four-character idioms with meanings, example sentences, and multiple-choice practice problems, with support for JLPT levels N1 through N5 and explanations in six languages including.
VocabularyJLPT and other testsIn JapaneseIdioms and proverbsJLPT N1Vocabulary listsExample sentencesJLPTJLPT N5FreeJLPT N2JLPT N4