This is a funny question to an Australian. Yous is commonly heard in Australia among people who are popularly referred to as bogans, but is also heard in the more regional parts of the country. A bogan is someone who is a little rough around the edges, probably poorly educated or sometimes just pretending to be (A 'bogan' who went to a private school since kindergarten is a particularly interesting phenomenon). As mentioned before though, it's not exclusive to bogans.
Anyway, it is generally seen as not proper English when used here which is funny because I hate saying 'you guys' or 'you all' and would like to be able to say "ya'll" or "youse". Sometimes I say, 'What are youse guys doing tonight?' to my friends for a laugh but as I said its usage is not widespread.
It's also spelt 'Youse' in Australia. See definition number 2: http://www.urbandictionary.com/define.php?term=Youse
These are specialized, field-specific terms from finance, accounting, and economics, and may have very specific definitions in some contexts (particularly accounting). I'll give you the general flavor, though.
Capital is generally a means to producing something else. For the most part, this word is used from the perspective of a business. Its capital consists of all of its resources (buildings, machines, patents, cash, etc.) that are used in the course of business. If the business has some wealth set aside but not likely to be used in the course of its business, it is less likely to be considered capital. When we use the term human capital, we are thinking of a person like a business. The skills, experience, and qualifications of a person are valuable tools that make their time worth something on the job market. The main message conveyed by the use of the word "capital" that it is a tool used to create wealth.
An asset is a more general term. It is anything that has value. There are real assets, which are physical or intellectual property that have value and can be sold. If they are being used to produce something, they may also be considered capital, but this is not necessary. There are also financial assets, which are things like stocks and bonds. These do not directly produce any real wealth. Instead they are contracts that entitle the owner to a stream of cash flows. It is not necessary that an asset be expected to make more money than it originally cost. The word "asset" conveys the idea that something is valuable and could probably be sold if you wanted to.
The meaning of the word investment depends on the context but generally means spending money in order to make more money. When a business purchases some new capital, that is considered an investment because it expects that capital to pay for itself in the future. An individual or financial intermediary is likely to make an investment by purchasing a financial asset (stock, bond, option, etc.). The word "investment" conveys the idea of sacrificing wealth today in order to have more wealth in the future.
There is plenty of overlap in these terms. A business investment may be capital, and some people may call it a business asset. An individual may make an investment, which is very likely to be considered an asset, but not capital.
Best Answer
The word Japanese is used as a singular and plural noun; it's incorrect to say Japaneses as a plural noun.
You can say either many Japanese (as a plural noun) or many Japanese people (as an adjective), but I think the latter is more common.