2018年5月現在、日本語に対応しつつある。
https://natural-language-understanding-demo.ng.bluemix.net/
natural-language-understanding - API Reference | IBM Watson Developer Cloud
https://www.ibm.com/watson/developercloud/natural-language-understanding/api/v1/
Natural Language Understanding | IBM Watson Developer Cloud
https://www.ibm.com/watson/developercloud/natural-language-understanding.html