As you may already be aware, the Japanese language includes honorifics and there are a number of different “levels” of politeness. Native speakers will adapt the language in subtle ways when speaking to colleagues in the office versus friends in an izakaya, for instance. Particularly in the business environment, honorifics are used to define the underlying power relationship, and from even just the briefest of conversations it will be clear who has the higher ranking within the company.
However, whether to use the polite form of the language is not just determined by the position or age of the person to whom you are speaking; it will also be used when ordering at a restaurant, asking for directions at a station, or meeting someone new.
Most textbooks will begin by introducing the honorific or polite form (represented by the addition of desu or masu at the end of the sentence). Because of its more formal and rigid nature—especially compared to English where we don’t have such a structured way of being polite—some learners of Japanese resent not learning straight off how to speak like “real Japanese” and, in response to this, some textbooks avoid introducing the honorific form altogether. This is a mistake and poor practice.
You will hear the honorific form spoken everywhere, every day. As mentioned above, it is used by native Japanese speakers when ordering a coffee or asking for help—it’s not just for speaking to your boss in the office. If a Japanese person were to walk up to a stranger and ask in the casual form for the whereabouts of the nearest train station, they would likely be met with a startled expression and a less than helpful reply. And it’s not just used by the older generation; teenagers will use it when meeting new people for the first time until they know each other well enough to switch to tameguchi—the informal way of speaking.
The problem is that because the standard and honorific forms are often referred to as “casual Japanese” and “formal Japanese”, connotations are inferred and parallels are drawn between “friendly” and “unfriendly”. On the contrary, when meeting anyone for the first time immediately using the standard or casual form might give the impression that you are speaking down to the other person; the formal way of speaking should be considered friendlier. To be clear, if even after getting to know someone of a similar age you continue to speak in this formal way then it might come off as a little cold and standoffish, but you will learn to know when to switch to the more casual form.
This linguistic display of deference to those we don’t know is foreign to English: a friend’s friend coming up to us with a “Hey, man!” and a slap on the back is nothing out of the ordinary. Books that only introduce you to the casual way of speaking Japanese are effectively trying to turn Japanese into English. The culture is part and parcel of the language—accept and embrace it!
Of course, as a foreigner learning Japanese you also have a full license to make such errors. No-one is going to think that you are being rude if you use the casual form when speaking to a stranger—just simply that you don’t know any better. But if one day you want to be able to converse without such special treatment it’s important to start off on the right foot.