Yakuza originated well before the times of the Samurai ended, but many of the samurai after the end of the meiji-restoration reasoned that there would be very little reminding them of the control, rights and feaudal system from before.
The Yakuza system seems to resemble or emulate this age old system very much, where honor and "justice" (if one can use that term) is all.
A famous sign of Yakuza (is or used to be) the tatoos that where mandatory.
One in particular, can be seen on the shoulder or back of some saying "Meiji to giri", more or less having been translated to me as "duty and honor" whereas it truly should be "Indebtedness and Duty"
No matter what you do, you're always in debt to someone for having what you have and being where you are, be it position, rights, rank or profits.
Per the same term, it would be highly disrespectful of Yakuza not to "take care of" the local area/its people as they owe great profits and priviliges to the same people for being active in their area.
And yes of course, they're brutal as hell sometimes, when they feel people deserve it, so that part is likely more true than not.
A guy mentioned something in another forum I frequent that was quite interesting.
In particular when talking about Kobe as it is a famous area with high frequency of Yakuza families.
He went to school in Japan as an exchange student and on the day of enrolment/sign in, the whole schoolyard was filled with students and he wondered what was going on and no one entered the school building.
Apparently some kid in a senior class, who was the son of a famous yakuza boss had used a katana for its original purpose and decapitated another kid who bullied his younger brother.
And he left the head on the stairs to the school as a warning sign.
Just as a general warning to the other kids not to touch his brother this year around.
If that is true or not, I dont know as I wasn't there, but I wouldn't put it passed them.
Say what you want about the Yakuza, but at the same token I dont quite appreciate all the drug-stuff and brutality affiliated with the subject, Ican clearly understand and appreciate their sense of loyalty, dedication and other parts formerly affiliated with the old traditions.