Picture the Z13 cipher text as a ring.

In this solution no characters will be changed. Characters will simply be added to the symbol slots. 

Plain text solution starts at the first M and is in Japanese

My name is —-

                 |

                 V

AEN+8K8M8XNAM

M8XNAMAEN+8K8

MAINAMAENWAKA

MAI NAMAEN WA KA

(My name is?)

Code opening is repeated. With the addition of a question mark and three curious characters. Quite possibly initials.

8X+

AIW

PLEASE KEEP PRIVATE FOR NOW