I agree with you.
Exactly, I bet this brother also learned these stuff over years of training and practice. Just coz you are a newbie, you are a bad guy- what logic is that.
It bothers me too, but mostly I blame his dad - the former president ffs - for deliberately not teaching him. Handovers are super important in business. Lil Bro is being a total jackass about it, but technically it's the responsibility of his own company to train him, so things can continue smoothly with the clients through the transition. It's bad for the company to do things this way, as well as making everything unnecessarily hard on Yukinori. His dad's being an idiot by throwing him in the deep end, no matter what he intends by doing things that way. It's not giving consideration to how the clients will react to mistakes, and how it will make his son feel to be belittled and criticised and have to apologise all the time. Grrr!
This bothers me since volume 1: how is he supposed to know how the job is done if NO ONE TEACHES HIM??? If you don't wanna teach him, you better be prepared to accept mistakes. He doesn't have a cristal ball to know the age of the your workers, pal. Hell, he's been doing this for only few months, he prob doesn't even know the names of all the people working directly under him. Ugh this was frustrating.