As explained in the ICU User Guide’s Regular Expressions page, you can use \p{script=foo} or [:script=foo:] syntax to filter by “script” Unicode property. Combining this with information from Wikipedia, you can use regular expressions like [[:script=Han:][:script=Hiragana:][:script=Katakana:]]+ to search for these characters.
However, this won’t include the spaces and other non-specific characters into the result, which might give you less-than-ideal results.