In Japanese business emails and phone calls, you will hear osewa ni natte orimasu constantly. Literally, the phrase refers to being in someone’s care or receiving their help, but in business Japanese it functions much more broadly than that.
When Japanese people say it, they are usually not stopping to think, “This person helped me with this particular thing.” Maybe the other person really has helped them somewhere along the way, but that is not the main point. In business, the phrase has become a standard greeting used when starting an exchange with someone you have a professional relationship with. In emails and phone calls, it can come out almost automatically.
It is most natural with someone you already have some kind of ongoing relationship with. Even so, hearing it from someone contacting you for the first time does not necessarily sound completely wrong. The two individuals may be speaking for the first time while their companies already have a relationship, and in practice, people do not always examine the phrase that closely.
The opposite is also revealing. If a business email jumps straight into the request with no greeting at all, it may not be outright rude, but it can feel a little abrupt. It does not have to begin with osewa ni natte orimasu, but some kind of opening phrase makes the exchange feel smoother.
Taken literally, the expression can be confusing for foreign learners. You may wonder, “What exactly have I done for this person?” Usually, that is not what the speaker is thinking about. The phrase works more as a way to acknowledge the professional relationship and move naturally into the actual topic.
So although osewa ni natte orimasu carries a sense of gratitude, in everyday business Japanese it also functions as a conventional opener. Rather than trying to attach a specific act of help to it every time, it is often more useful to think of it as: “We have a business relationship, so this is how I begin.”