Shishi Masaru (Japanese: 獅司 大) born 16 January 1997 as Serhii Sokolovskyi (Ukrainian: Сергій Соколовський), is a Ukrainian professional sumo wrestler from Melitopol, Zaporizhzhia Oblast. Nicknamed "mini-Baruto", he made his professional debut in January 2020 after a successful amateur career. He became sekitori when he reached the jūryō division in July 2023, and was promoted to the top makuuchi division for the first time in November 2024. He wrestles for Ikazuchi stable, and joined that stable when it was still named Irumagawa.
As of July 2023 he is one of the two Ukrainian currently competing in professional sumo. He is the first Ukranian in the history of the sport to have reached the status of sekitori, and the only such person to be promoted to the top division.