Matagu Shidoh is a supporting character in the anime Please Teacher! He is a high school student and a close friend of the main protagonist, Kei Kusanagi, as well as a member of the tight-knit group of classmates around whom the story revolves. He has short black hair and brown eyes, and he is the older brother of Haruko Shido.

His most defining trait is a serious and studious demeanor, particularly his deep interest in astronomy. This passion is so central to his character that his fondest dream is to meet an extraterrestrial being. A running dramatic irony in the series is that his teacher, Mizuho Kazami, is secretly a half-alien officer from the Galactic Federation, yet Matagu remains completely unaware of this fact despite interacting with her regularly. He even develops a romantic crush on Mizuho and at one point considers confessing his feelings to her, but his inherent shyness prevents him from following through.

Personality-wise, Matagu is often described as a classic nerd and the most hopeless member of the group when it comes to romance; by the end of the series, he has never managed to enter a relationship. He is far less confident and self-assured than his friend Hyosuke Magumo, and even less so than Kei. This lack of confidence, bordering on crippling shyness, is a key aspect of his character. Nonetheless, within the friend circle, he is regarded as the smartest and most serious individual, often providing a grounded, analytical perspective.

In the story, Matagu serves as a loyal friend who adds a touch of comedic relief through his obliviousness about Mizuho's true identity and his earnest but unsuccessful romantic aspirations. His role does not involve significant personal development or dramatic change; he remains consistent throughout the series as the studious, shy astronomy enthusiast who never achieves his dream of meeting an alien or winning the girl he likes. His notable abilities are primarily intellectual: a strong aptitude for astronomy and a serious, focused approach to his studies.