Oyabun

Literally 'parent role'. The leader for a Yakuza organization. He's the father figure for the clan or house of Kobun, those in the 'child role'.
The oyabun is at the top of a pyramid based group or syndicate and exercises total control over those under him. Absolute obedience and loyalty to him are required. All kobun pay him monthly dues and/or tribute payments. Protecting him is of utmost importance. Clan members are expected to sacrifice themselves willingly for his benefit--whether that means going to jail in his stead or dying to protect him.

...if the oyabun says the passing crow is white, then the kobun must agree.¹

Qualifications

Leadership skills, enforcement (utilizing violence), and occupational skills (to increase the clan's finances) ³

Appointment

The retiring oyabun picks a successor, which must meet the agreement of the rest of the clan so there isn't a split in the group. This is the one exception to the oyabun's absolute control. ³

Duties

Providing for the needs of those under him via leadership and financial gain through illegal and legal activities

References

¹ - The Japanese Mafia: Yakuza, Law, and the State, 2003 edition, p. 73
² - YAKUZA: THE WARLORDS OF JAPANESE ORGANIZED CRIME
³ - Japanese Patterns of Behaviour

Alternative Naming

the Boss, 親分 (おやぶん)

Equates to

Warlord, godfather/boss in Italian mob

Related Organizations

• Yakuza

Liminal Chronicles Notes

While we only meet Umeji Tatsuya's and Otsuka Hiro's oyabun in the side-story Initiation, his iron-fisted influence is still present in the first book. I also chose to show the group's respect for him in 'Initiation' by not revealing his face until Umeji has to lift his head in the ceremony.