This is an explanation about organization structure in yakuza, that I use in this story, so that you readers will not be so confused when reading FHF!

A. in yakuza worlds, the yakuza members are divided into clans. In this story, Example of clan is Sooman Clan.

B. Clans are structured. The highest position in a clan is the Chairman, a.k.a the overall boss. Example of chairman is Lee Sooman, the chairman of Sooman Clan. Under the chairman, there are clan lieutenants, who usually are the strongest, or the highest rank members of each families. Beside clan lieutenants, there are also senior advisors and headquarters chief.

C. Under each clans, there are families. Examples of families are Kim family, Choi family, etc.

D. Families are structured. The highest position in a yakuza family is the head, or head patriarch. Examples of head of family in this story is Heechul, the head of Kim family in Sooman Clan. Under the head of family, there is junior leader  (if the head of family have son/daughter), and under junior leader there are first lieutenant and second lieutenant. First lieutenant takes care of the regional gangs, second lieutenant takes care of local gangs. 

- Shortly said : Clans > Families

Clans : Chairman > senior advisor, headquarters chief > clan lieutenants

Families : Head of family > junior leader > first lieutenant > second lieutenant lieutenant > gangs

Extras :

A. Every yakuza members are ranked; higher the rank, more appreciation you will get, and higher position you will get (such as lieutenants, junior leader, or even head of family). Rank are determined based on strength, intelligence, or loyalty. That's why Sehun agreed to do that massacre, because it shows his loyalty to his clan and it will raise up his rank.

B. Yakuza members doesn't have to have the same last name with their yakuza family (ex. Choi Minho didn't have to be in the Choi family, he can be in Lee family if he wants to). Your family in yakuza is decided by which head of family that you want to be loyal with.

C. Yakuza clans are even ranked. Higher the ranks, public will respect them higher and payment for their jobs are higher as well. Clan ranks are determined by their area coverage, the total of their families and members, and also their strength.

This chapter will always be updated if there are any new necessary informations.

Happy reading! :D