Dear Professor Susan M. Garreis,

Haruka, my name is M. Susan Garreis.

I'm writing this letter to you for the first time.
My name is Oikawa Haruka.Please call me Haruka.
I live in Tokyo. Tokyo is the biggest city in Japan.

Tokyo is an amazing city. I am sure it is bigger now than when I visited in 1987.

My major in college is information technology
OR
I am taking a course in information technology
>I am not sure what you meant to say.

and I am studying modern Japanese economics and marketing.

What was particularly difficult for you when you were a working parent?
1. Being available to my children when they needed me, either physically or emotionally.
2. Being able to go to their school concerts or plays. 
3. Finding time to help them with their homework.
4. Finding time to just have fun with each one.
5. Finding time to be with my husband. I never succeeded in that. That's one of the reasons we divorced.
6. Making up the time I took off from work to take my kids to the doctor or to go to a school function. Sometimes I worked all weekend. Not fun.

Also, how did you contrive to make them compatible?

>I never succeeded in making them compatible. I know very few women who are or were satisfied with their work-life balance.

My hobby is listening to music, reading, and talking with friends. I read various books and listen to various music. And I talk about various things to my friends and listen to the stories of my friends.
>What is the latest book you read for fun?
>What type of music do you lie best?
>Since I retired I can read as much as I want. I love to read murder mysteries. The book I am reading now is Death In Holy Orders by P. D. James. An English Inspector tries to learn why a man studying to be a priest was murdered at his seminary.
>I enjoy listening to country music. I listen to music on my car radio.
>I, too, enjoy meeting my friends and sharing stories with them. I meet every month with two friends from college. We spend the afternoon together at a local restaurant. It's great. We have known each other for more than fifty years.

I'm not good at English. 
So my English isn't good enough.

But I will actively try to do my best.
>Your written English is pretty good already. I am sure it will improve during this course. It will take a great deal of time on your part. It will stay with you for the rest of your life.

Thank you in advance. 

I’m waiting for your reply.
>Haruka, I got three "first messages" each with a slightly different title in the subject line. Since the contents were the same in each, I replied only once. Less translating for you.

Sincerely yours,,,
>only one comma after "sincerely yours"

Haruka.