Kotlin unicode-block regexes for extracting various Japanese char types to a string list.

JapRegexUtils.kt

// see: http://www.localizingjapan.com/blog/2012/01/20/regular-expressions-for-japanese-text/
val fullWidthHiraganaRegex   = "[ぁ-ゟ]".toRegex()
val fullWidthKatakanaRegex   = "[゠-ヿ]".toRegex()
val kanjiRegex               = "[㐀-䶵一-鿋豈-頻]".toRegex()
val radicalsRegex            = "[⺀-⿕]".toRegex()
val halfWidthKatakanaRegex   = "[ｱ-ﾝ]".toRegex()
val fullWidthAlphaNumRegex   = "[！-～]".toRegex()
val japSymbolsRegex          = "[、-〿]".toRegex()
val miscSymbolsRegex         = "[ㇰ-ㇿ㈠-㉃㊀-㋾㌀-㍿]".toRegex()
val asciiCharsRegex          = "[ -~]".toRegex()

// use the regex passed in to extract any matches to a List<String>
fun Regex.extractToList(textIn:String) : List<String> {
    var rv = mutableListOf<String>()
    this.findAll(textIn)?.forEach { rv.add(it.value) }
    return rv
}

Use assuming you put file in same directory as caller class:

import kanjiRegex
import extractToList
...
val kanjiList = kanjiRegex.extractToRegex("String with kanji: 皆たち、こんにちは。")

would return a single element list containing "皆"