Mikiya Okuno works in MySQL support and is a long-time advocate of free software. He is the author of two MySQL books in Japanese published by Gijutsu-Hyoronsha: MySQL Cluster構築・運用バイブル (2012), the first Japanese-language guide to MySQL Cluster, and エキスパートのためのMySQL［運用+管理］トラブルシューティングガイド.
With Jesper Wisborg Krogh he co-wrote Pro MySQL NDB Cluster (Apress, 2017).