The "Ryou-Un Maru", a fishing vessel in the Japanese merchant fleet, was originally built around 1982. It was owned by a Hokkaido-based fishing company and was used for shrimping or squidding. After a long service career the ship's owner decided it was too old for continued use and moored it in Aomori Prefecture in Honshu pending sale. When the Tōhoku earthquake and tsunami struck in March 2011, "Ryou-Un Maru" broke free and was set adrift.