Morphological analysis is used to decompose sentences in Japanese into words. Tools for morphological analysis, such as MeCab, can be used to break sentences into words. However, this morpheme analysis has weaknesses. That means that it can not be used for unknown words.
So there is Character - level CNN. (https://arxiv.org/abs/1509.01626)
Character-level CNN is a method that began to be seen around 2015. One of the features is that no morphological analysis is necessary. Enter the sentences in CNN in character units, put them in the feature map, and pour them into the entire tie layer to learn the classification.
