This uniform is worn by Yuri when she invaded and disguised her identity for secret bomb research. Nobody felt suspicious that she might be a bomb expert.
You will receive an extra bonus of 20% EXP and 25% of points if you play with this character.
In other versions of CSO, Yuri is named as Anna. Hinting that she may have Russian heritage.
This is one of the few female characters who does not come with a custom background when selected in the shop or barracks. The others are Alice (Limited Edition), Lingling and Isabelle.