Re-entry to Japan and permit

hi guys,

I was an exchange student last year form 2015/09/15 September to this September. I went back to my country already.
At the end of this month, I have a conference and need to go back. My visa is valid until December and I did fill the embarkation form before leaving and my resident card remains without any hole.
So I wonder whether I can use the visa I got last year or not, please help me asap.

Thank you

My visa is valid until December and I did fill the embarkation form before leaving and my resident card remains without any hole.

Ok, this is one of those questions where terminology really matters. So basically:

1. You entered Japan on a student visa in 2015. At that point you were given residency as a student and the visa itself has served its purpose and is no longer usable to enter. The date printed on it is when it has to be used by. Since you entered, it is no longer valid.

2. You left Japan last September. Did you keep your residency (checked the special reentry permit box on the form?). If so then you can enter again up to the expiration of your current residency. That will be printed on the residency sticker in your passport. Otherwise you may need a new visa to enter Japan.