I don't need to know as long as it's credible. However, given the general knowledge of mob culture and the Yakuza movie sub-genre, I should think the question may come up sooner rather than later.
Hate to keep harping on it but even though it's a logline for a series, it still needs more specificity as to the action, the plot of the pilot episode. How is he supposed to prove his "mettle and loyalty". By what specific mission, ritual or test that marks his rite of passage into the netherworld of crime?
To repeat, I'm talking about is the all-important pilot episode. There are so many competitive venues and programs for an audience's attention -- and more every season -- a pilot for a series has to stand out from the opening scene, has to grab an audience by their eyeballs and not let go. That requires a strong plot for the pilot that can stand on its own.
My personal gold standard for a pilot kicking off a series is the one for "Breaking Bad". When a mild mannered high school chemistry teacher is diagnosed with fatal cancer, he starts cooking meth to pay the bills and provide for his family after his death. (29 words). All the complications, all the episodes, all the seasons follow from that kick-off plot.
So what's the plot for the pilot episode?