The Wave Single Championship is a women's professional wrestling championship owned by the Pro Wrestling Wave promotion. The title is nicknamed and more commonly referred to as the Regina di Wave Championship . The championship, which is situated at the top of Pro Wrestling Wave's championship hierarchy, was first announced on December 5, 2012. The inaugural champion was crowned on March 17, 2013, when Yumi Ohka defeated Kana in the finals of a five-woman tournament.

Mio Shirai is a Japanese former professional wrestler and current professional wrestling referee. She started her career in March 2007, working alongside her sister Io Shirai on the Japanese independent circuit for promotions such as Ice Ribbon, JWP Joshi Puroresu and Pro Wrestling Wave. In June 2010, the Shirais came together with fellow freelancer Kana to form the Triple Tails stable as part of which they began working most notably for Smash. After Io left the stable the following year, Mio and Kana continued working together as the tag team Triple Tails.S. Shirai remained a freelancer until January 2014, when she signed a four-way contract with Ice Ribbon, Oz Academy, Pro Wrestling Wave and Union Pro Wrestling. She retired from professional wrestling due to neck injuries in September 2015 at the age of 27, after which she started working as a referee.