Shinobu Tsukasa, also known as Kenichi Shinoda, is the Yamaguchi-gumi's current oyabun.
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The oyabun-kobun relationship is formalized by ceremonial sharing of sake from a single cup.
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Those who have received sake from oyabun are part of the immediate family and ranked in terms of elder or younger brothers.
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Sometimes an underboss may do this in penance to the oyabun if he wants to spare a member of his own gang from further retaliation.
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The chain of command is more lax, and although Shigeo Nishiguchi is always the supreme oyabun, its leadership is distributed among several other people.
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Sugai drops Nick at the outskirts of a remote farm where a meeting of the oyabun, the other crime bosses of the region, is to take place.
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However, each kobun, in turn, can offer sakazuki as oyabun to his underling to form an affiliated organisation, which might in turn form lower ranked organizations.
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A Japanese supervisor
The Father. The absolute leader in a Yakuza clan. He has an advisor called a Saiko-komon. Besides that he has an army of advocates, accountants, secretaries and advisors
(Jap.) : The head of a Yakuza clan (lit. "parent of high status").