A sniper. Her mother is German, her father American. Growing up, Touka learned self-defense techniques and riflery from her father, a former soldier, and his comrades; she was the youngest ever winner of a shooting competition in her hometown. In the wake of her mother's death, she spent two years attached to a PMC (private military contractor) alongside her father.
She can be extraordinarily belligerent, and sometimes breaks into outbursts of violence. She is, in short, a classic tsundere. Though infinitely curious about the world, she has a pragmatic side, too: she won't tolerate any nonsense. She possesses a measure of shrewdness and inner strength that belies her cute, childish exterior.
Whenever she was left home alone as a child, Touka would shove a shotgun in the face of any cold-caller who came knocking; she's since become known for her shyness around strangers. She tends to take an instant dislike to anyone she meets. She's clearly desperate to be regarded as a friend by others, though, however little effort she exerts in this regard herself.
She's basically pretty bad at making friends. She also has a bit of a complex about her small stature, and it's to compensate for this that she tries to act all grown-up.