Origin Star Trek Canon Special Note
Not everything listed in the origin is Canon. That is because only television shows and movies are considered canon for Star Trek. This being a comic website there are many things here that are not canon. So unless it is contradicted in film it should be listed as part of the character biography.
Yssir is an Andorian woman. She only appears in an alternate timeline and it is unknown what she does in the regular timeline. In the alternate time line She serves on the cargo Ship Bounty. Her post aboard the Bounty is the Ops position. Her Captain James Kirk find's a young woman named Mia Colt. In his attempt to return Mia to her timeline Yssir is killed.