Notorious are the Japanese when it comes to learning languages, even though there is a fairly large language education market in Japan. A lot of lay Japanese people want to learn a language like English from a native speaker of it because they believe that a native speaker must be an expert and that must be the best solution. It is fine if they want it that way as long as it motivates them, but there is something that they never think about: what exactly is a native speaker? In applied linguistics, it is widely accepted that a native speaker of a language is someone who acquired the language at an early age from people like his/her parents, who take care of the person. A native language is often called an L1 if that is the person's dominant language. There are also L2, L3,..., and Ln if the person has acquired more than a language. An L2 is one's second most dominant language, and an L3 is one's third most dominant language, and so it goes on.
What people usually don't understand is that not all native languages function as an L1. There is, of course, a difference between acquiring a language at an early age and being most fluent in that language later. For example, it can happen when you pick up Language A from your parents and later become more fluent in Language B, which happens to be the medium at school and university. It can also happen when you are a speaker of Language A who move to a place where Language B is spoken when you are still young. Your L1 can change when you put less priority on learning your native language and switch to another for one reason or another.
Moreover, the time has changed for some languages. English, for example, has been diversified so much that it has been considered as Englishes for at least the last decade. That means that English is no longer regarded as a single language that the Anglo-Saxons speak. Instead, it has been splitting into multiple languages due to contact with other languages. It has been more and more difficult to define what exactly English is, and what is important here is that even those Englishes are not just learners' English but also native languages for some people.
It is not only learners that are ignorant. Most employers in Japan, including language schools, want to hire 'native speakers', but they have no freaking idea about these facts. This is the case in some other countries as well. People often think of you as a weirdo when you contemplate how language functions, but these things are worth considering in daily life.