Kirk here with information about opportunities to take Japanese language classes. The information came to me through “Safety and Security disaster prevention and lifestyle information newsletter” put out by the Kumamoto International Foundation. Here’s the English and Japanese text in the newsletter about studying Japanese:
【The study of Japanese】 The intensive beginner’s Japanese language course “Hajimete no Nihongo” will be held from 3rd July (Mon) for those who have just arrived in Kumamoto and know little or no Japanese. If you would like to participate, please apply to the Kumamoto International Foundation. For more information, please visit the website below. https://www.kumamoto-if.or.jp/kiji0031715/index.html
[Note from Kirk: Much of the page is in Japanese but it lists a phone number and an e-mail address, either of which you can use to inquire in English. However, the flier lists a different e-mail address – [email protected] – as the e-mail contact and so I think that may be most appropriate.]
【日本語学習について】 熊本に来たばっかりで、ほとんど日本語がわからない人、日本語を勉強したことがない人を対象に初級日本語集中講座「はじめてのにほんご」を７月3日（月）から開催します。 参加したい人は熊本市国際交流振興事業団へお申し込みください。 詳しい内容は下記のホームページで https://www.kumamoto-if.or.jp/list00066.html
P.S. If you have other good leads about study opportunities (classes, groups, exchanges, etc.) please post about them in a comment.