Sashi is the most serious and intelligent of the three, and pays more attention than the others do. In every dimension, she, Penn and Boone travel, it is her duty to describe their mission and what to expect in each world. She hates being mocked, yet some forms she takes are too humiliating for the others to take seriously (such as a clown or a cute fluffy stuffed animal). She is very aggressive, skilled at combat, and likely to threaten others no matter what side they are on. However, she does have enough faith in her friends, Penn especially, to be a trustworthy sidekick, and tries her best to be respectful to others as well. In "Flurgle Burgle", she is given credit for making a completed mission possible, and is congratulated with a cake that she is almost sickened by, but accepts as a reward.
Sashi is a short asian girl with dark brown eyes and dark brown (or white) hair with violet and yellow highlights at the tips held back by two ponytails. For makeup, she wears purple eyeshadow. She wears her specs with light blue rims, maroon gloves, and a long-sleeved sky blue shirt with purple and blue lines at the wrist ends underneath a red-violet vest with a yellow circle on the left side of her chest.
She wears a red-violet miniskirt, different styled socks (her left sock a solid purple and her right sock with different shades of mauve stripes), and white boots with a purple line down the front and yellow circle on the sides. Around her left knee, there is a red-violet strap with a white circular object over her knee cap.
As of At the End of the Worlds, her hair is now short and straight, and has pink tipped ends.
- In "3 Big Problems", she is good at dodgeball at gym class.
- For Sashi's art project in "The Princess Most Fair", she brings a smashed television.
- Sashi's first name is an Indian name that means "moon," and her last name, Kobayashi, is a Japanese surname that means "small forest."
- As revealed in "Totally into Your Body", Sashi has a crush on an older student name Teddy.