In the second onFurthermore, I'd like to become friends with foreigners to play video games Ithat we both like together.

If my English skill improves, then I’d likbe able to play the game togewith others.

TheMy last reasone is very simple, but it’s important to me.

My Story - Why Do I Learn English

"Why I learn English" or "Why do I learn English?" both work

I have three reasons tofor learning English.

First of all, it’s the most important of reasonsand foremost, I learn English to continue wormaking to make money for my lifea living and to support my family's life.

'making a living' is a good english phrase for what you mean here

Now in Japan, Japanesthe populations are is decreasing year by year.

more of a style thing, but once you say Japan once you don't have to specify that it is the Japanese population you're talking about.

When that happens, if I can’t communicate with them in English, then I can't be working and I may be fired soon.

So I'm learning English to avoid being fired.

In the sSecond onely, I'd like to become friends with foreigners toso we can play video games I like together.

There are mMany foreigners in the world ofplay theis game, but I can’t communicate with them because I can’t speak fluently and type chat quickly in English.

To beBeing able to speak English fluently is very cool, I think.

That'sose are all of the reasons why I'm learning English.

Since you have multiple reasons it's plural and 'those' not 'that'

I'd like to talk to you about why I'm learning English.

you are still learning English, so you say "I'm learning" instead of "I learn"

First of all, it’s the most important of reasonsand foremost, I learn English to continue working to make money for my life and to support my family's life.

"First and foremost" means "first and most important", so it's a shorter/smoother way to say what you wrote :)

Now in Japan, the Japanese populations are is decreasing year by year.

When that happens, if I can’t communicate with them in English, then I caouldn't be working and I may becould get fired soon.

So, I'm learning English in order to avoid begetting fired.

"in order to" sounds nicer here as just "to"

In the sSecond onely, I'd like to become friends with foreigners to play video games I likewho like the same video games as I do, so that we can play together.

I especially like Final Fantasy 14 that, which is an online game.

There are many foreign players in the world of theis game, but I can’t communicate with them because I can’t speak fluently and type chat quickly in English.

If my English skill improves, then I’d like to play the game togewith others.

The last reasone is very simple, but it’s important to me.

That's all of the reasons why I'm learning English.