Dobrynya Nikitich
As Japan had no prior experience in building icebreakers, the IJN began by observing icebreaker architectures of neighboring countries, and decided to base "Ōtomari" on the Russian icebreaker "Dobrynya Nikitich". The IJN hurried the construction of "Otomari", because they wanted her by the Winter of 1921, and she was launched less than four months after her keel was laid down.