Ikura's father

 was the father of Ikura. According to his son in "The Dark Side of the Kobushido", he was eaten by Néko when Ikura was only little.

Trivia

 * In order to trick Ikura into forming a makizuki rebellion against the sushis at the restaurant, Ebi pretends to be a "spirit" of Ikura's father in "The Dark Side of the Kobushido".