This book constitutes the refereed proceedings of the 19th International Symposium, KSS 2019, held in Tokyo, Japan, in November 2018. The 20 revised full papers presented were carefully reviewed and selected from 54 submissions. This year KSS 2018 provides opportunities for presenting interesting new research results, facilitating interdisciplinary discussions, and leading to knowledge transfer under the theme of "Knowledge Acquisition from Structured and Unstructured Data for Effective Social Implementation".