headstrong, impulsive, eccentric, stubborn, funny, tomboyish, talkative, kind but can get angry

headstrong, impulsive, eccentric, and stubborn

Rarely smiles. loves Salmon Daikon. A skilled swordsman. Stoic. Serious. Likes Rengoku, Tengen, Tanjiro, Mitsuri, Muichiro and Gyomei.

Stoic, Rarely Smiles, depressed

WO-1 Prototype 1 is an emotionless robot programmed to give life lessons and speak in a casual way

Emotionless

Despite having formerly attained a position in the elite Gotei 13, Mashiro has very childish and immature mannerisms. She is portrayed as rather flighty and rarely takes note of the bigger picture around her. She is prone to throwing fits over the smallest of things. 
In battle, she is somewhat more serious though, acting slightly like a superhero while attacking and after winning.