Bulgarian-born sumo wrestler Kaloyan Mahlyanov "Kotooshu" has announced his retirement from Japan's professional sumo.

Kotooshu, who recently became a Japanese citizen and changed his family name to Ando (from his wife's name), announced his retirement a day after pulling out of the March Grand Sumo Tournament in Osaka. He had been having a poor run of 1 win and 9 losses prior to the decision of stepping down.

Kotooshu, who became the first European wrestler to lift the Emperor's Cup, in 2008, also managed to reach the second highest rank in sumo – "Ozeki". His illustrious 12-year career in the land of the rising sun made him one of the most popular faces of the sport, as well as Bulgaria's best-known export since the yoghurt boom.

The Djulyunitsa-native takes off the "mawashi" (belt) following 537 wins and 337 losses. Over the past 2 years, he was troubled by multiple injuries, which were behind his sudden drop of form.

The 202-cm wrestler has openly expressed his desire to remain in Japan and become an "oyakata" – sumo coach. This is also the reason for his switch of nationalities, as Japanese sumo does not permit foreigners to become coaches.