"Negao wa Micha Iya" is a manga series that explores themes of identity, self-perception, and societal expectations through its protagonist, a young woman named Micha. Micha struggles with her self-image, feeling unattractive and out of place due to her plain appearance. Her life takes a turn when she discovers a magical lipstick that temporarily transforms her into a stunningly beautiful version of herself. This newfound beauty grants her confidence and opportunities she never imagined, but it also complicates her relationships and forces her to confront the superficiality of those around her.

As Micha navigates her dual identities, she becomes entangled in a love triangle involving two men: a childhood friend who has always seen her for who she truly is, and a popular, handsome classmate who is drawn to her transformed self. The story delves into the tension between Micha's desire for external validation and her growing realization that true self-worth comes from within. The magical lipstick serves as a metaphor for societal pressures and the lengths people go to in order to fit into conventional standards of beauty.

Throughout the series, Micha's journey is marked by moments of self-doubt, growth, and introspection. The narrative examines how her reliance on the lipstick affects her relationships with friends, family, and romantic interests, as well as her own sense of identity. The story balances lighthearted moments with deeper emotional undertones, creating a nuanced exploration of self-acceptance and the complexities of human connection. The supporting characters, including Micha's friends and love interests, play significant roles in shaping her experiences and challenging her perceptions of beauty and worth.