Kotooshu, the first European wrestler to ever win an Emperor's Cup and achieve sumo's second highest rank of ozeki, retired Thursday.

The Bulgarian rikishi, whose real name is Karoyan Ando, submitted his retirement papers to the Japan Sumo Association the same day. He said he has reached his physical limit and no longer possesses the energy to continue wrestling.

Kotooshu, 31, was promoted to the ozeki rank in January 2006 and served at the second highest rank for 47 tournaments — the fourth longest on the all-time list.

At the ongoing Spring Grand Sumo Tournament, Kotooshu lost nine consecutive bouts from the second day and withdrew from the meet on Wednesday, the 11th day, with a shoulder injury.

Kotooshu, who obtained Japanese nationality in January, plans to instruct junior wrestlers. As an elder in the JSA, he will be known as stablemaster Kotooshu. Wrestlers who achieve the rank of ozeki can retain their ring name for three years after retirement.