プロレスリングWAVE
On December 15, 2015, it was announced that Shirai would start working as a referee under the ring name Mio, written in Roman script and stylized in all capital letters. She made her debut in the role at Ice Ribbon's "RibbonMania 2015" on December 31. In January 2016, Shirai began refereeing matches also for both Oz Academy and Pro Wrestling Wave. On August 16, it was announced that Shirai was officially joining Ice Ribbon's staff on September 1. In addition to continuing to work as a referee for the promotion, she would also take over the Puroresu Circle training duties.