It has been said among whaling experts in Hokkaido that the so-called "Tsuchi kujira"(Baird's beaked whale) has two types and a type is called "Kurotsuchi"(black Baird's beaked whale) or Karasu(Crow), which are darker and smaller in colour than regular Baird's beaked whales, but their true identity has not been clarified then.
The three black Baird's beaked whale collected in Hokkaido since 2008 by the cetacean research group "Stranding Network Hokkaido" (SNH), whose secretariat is the Matsuishi Lab. of Hokkaido University, had the characteristics of Baird's beaked whale genus, such as blow hole morphology, but their external morphology, including the head, was different from the previously known Baird's beaked whales. Kitamura et al. (2013) compared DNA sequences extracted from these three black Baird's beaked whales and 67 known Baird's beaked whales, which
were known in the literature. The results showed clear differences, raising the possibility of an unknown species of Baird's beaked whale that differs from the known species. Subsequently, Morin et al. (2017) reported that an unknown individual with a similar genetic composition also inhabits the Aleutian Islands. In order to describe this unknown species as a new species, it was necessary to understand its morphological characteristics and clarify its relationship to the two known species of the genus beaked whale (Arnoux's beaked whale and Baird's beaked whale) through comprehensive analysis.
