This is regex for who looking for regex japan text -->

japan_regex.php

<?php 
#### DEFINE ####
const REGEX_JAPAN_TEXT =
    '/[^\x{3041}-\x{3096}' . // Hiragana
    '\x{3400}-\x{4DB5}\x{4E00}-\x{9FCB}\x{F900}-\x{FA6A}\x{2E80}-\x{2FD5}' . // Kanji
    '\x{FF5F}-\x{FF9F}' . // Katakana (Half Width)
    '\x{30A0}-\x{30FF}]/u'; // Katakana (Full Width)
const REGEX_HIRAGANA = '/[^\x{3041}-\x{3096}]/u';
const REGEX_KANJI = '/[^\x{3400}-\x{4DB5}\x{4E00}-\x{9FCB}\x{F900}-\x{FA6A}\x{2E80}-\x{2FD5}]/u';
const REGEX_KATAKANA_HALF = '/[^\x{FF5F}-\x{FF9F}]/u';
const REGEX_KATAKANA_FULL = '/[^\x{30A0}-\x{30FF}]/u';

#### Using ##### 
$inputValue = 'ァ ア ィ イ ゥ ウ ェ エ ォ オ カ ガ 0 1 a b c'
$strJapan = preg_replace(REGEX_JAPAN_TEXT, "", $inputValue); // it will be get ァアィイゥウェエォオカガ only