One thing you should know about Unicorn Store: The unicorn is not metaphorical. We're introduced to Larson's Kit just as she gets kicked out of art school for painting a neon-and-glitter Pollock approximation that's not to the liking of her stuffy teachers. To be fair, a wide shot suggests the assignment was to paint a self-portrait, and Kit has obviously interpreted the directive in abstract terms.
She retreats home, where her overeager parents (Joan Cusack and Bradley Whitford) try to feed her healthy meals -- she hates kale -- and set her up with an employee at their business, a sort of therapeutic camp called "Emotion Quest." She decides to get a temp job, and around the same time she starts receiving mysterious letters inviting her to "The Store." This turns out to be the titular Unicorn Store. There she meets a man known only as "The Salesman," a sort of Wonka-esque figure played by Larson's Captain Marvel co-star Samuel L. Jackson, who dons brightly colored suits and wears tinsel in his hair. He explains that if she can prove that she's prepared to house a unicorn, he can get her one.
The plot then aimlessly drifts as Kit preps for the arrival of her unicorn. She enlists an amiable hardware store employee, Virgil (Mamoudou Athie), to help her build a stable, and starts dying hay different colors. (I guess unicorns eat rainbow hay.) Meanwhile, her parents are growing increasingly concerned, and her boss (Hamish Linklatert) is becoming increasingly creepy.
In front of the camera, Larson is as engaging a performer as ever, but Samantha McIntyre's erratic script makes it hard to pin down exactly who Kit is as person beneath all that affection for a Lisa Frank aesthetic. She's almost disconcertingly naive at times, like when she asks Virgil if her superior at work is sexually harassing her. (He clearly is.) In this sense, she reminds me of another Netflix heroine: Kimmy Schmidt, except Kimmy spent most of her formative years in a bunker. Kit -- as far as we learn -- did not. In a crucial monologue (spoilers, I suppose), she reveals her parents never got her pet in her youth, but that fails to resonate as a source of any real trauma. She craves unconditional love, but never considers that having meaningful relationships with other humans means compromise.