Congrats on your job!
I don't know about how it's like in Japan, but in many Japanese restaurants (in America) whose kitchens I've visited or guested in, patina is not looked down on, in fact, many chefs force a patina. But bear in mind, this is a gentle patina, not making a knife look like it was made from a corroded steel bucket. I know a James Beard winner and have been in his kitchen and his knives are very gently patina'd.
But I might agree that the type of knife it is might make a difference. "White" or "blue" steel does have a distinctive look. Damascus blades are expected to have color differences. But if someone is using a sandvick knife, CPM or other stainless knife and it was corroded, I'd worry