IKuromojiStemmerTokenFilter
The kuromoji_stemmer token filter normalizes common katakana spelling variations ending in a
long sound character by removing this character (U+30FC). Only full-width katakana characters are supported.
Part of the `analysis-kuromoji` plugin: https://www.elastic.co/guide/en/elasticsearch/plugins/current/analysis-kuromoji.html
Katakana words shorter than the minimum length are not stemmed (default is 4).