"Hello, this is Terumi." is a manga series that centers on Terumi, a high school student who leads a double life. By day, she is an ordinary, unassuming girl, but by night, she transforms into a popular online streamer under the alias "Teru." Her streaming persona is confident, charismatic, and wildly successful, attracting a large following. However, Terumi struggles to reconcile her two identities, fearing that her classmates or family will discover her secret. This tension drives much of the narrative as she navigates the challenges of maintaining her anonymity while balancing the pressures of school, friendships, and her online career.

The story explores themes of identity, self-expression, and the impact of social media on personal relationships. Terumi's interactions with her classmates, particularly her close friend Yui, highlight the contrast between her real-life shyness and her online boldness. As her streaming career grows, she faces dilemmas such as dealing with online harassment, managing her time, and confronting the ethical implications of her anonymity. The series also delves into the lives of her viewers and fellow streamers, providing a broader perspective on the online community and its dynamics.

Key characters include Terumi, whose internal conflict forms the emotional core of the story; Yui, her supportive but sometimes oblivious friend; and various online personalities who influence Terumi's journey. The narrative balances slice-of-life moments with dramatic developments, creating a compelling exploration of modern youth culture and the complexities of living in a digital age. The manga avoids oversimplifying its themes, instead presenting a nuanced portrayal of its protagonist's struggles and growth.