Can't wait! -> (Okay because it is a title, but usually this would need a subject.)

It is almost a year and half! (I am from Japan) -> It's been almost a year and a half! (I am from Japan.)

I decided to back to my country in this winter because there is ceremony to cerebrate people who become 20. -> I decided to go back to my country this winter because there is a ceremony for people who are turning 20.

I am happy I can see my family and friends! -> (Good)

I have been missing Japanese food, so I'm gonna eat tons of Japanese food when I go there, and I'll be fat. haha -> I have been missing Japanese food, so I'm gonna eat tons of Japanese food when I got there, and I'll get fat. haha.

Thank you for seeing my notebook! -> Thank you for looking at my notebook!

If you have any corrections to this notebook, I'd like to know it. ->If you have any corrections, I'd like to know.

*Nice entry! I hope you enjoy your time back in Japan and eat as much Japanese food as you can! :)