Miyo, often called Miyo-chan, is a minor supporting character in Tanaka-kun is Always Listless. She is one of the close friends of Shiraishi, the class president. In terms of appearance, Miyo is a short girl with blue hair and a small beauty mark, or mole, located under one of her eyes. She stands at 155 centimeters tall. Her birthday is October 13, and her blood type is A.

Miyo's role in the story is primarily defined by her friendship with Shiraishi. Together with her other friend Yoshitaka, Miyo acts as a supportive and watchful presence for Shiraishi. She is part of Shiraishi's immediate social circle at school and looks out for her. The available information does not describe a distinct personality beyond her role as a caring friend, nor does it indicate strong personal motivations or a character arc. Miyo is a background figure who contributes to the slice-of-life atmosphere by being part of Shiraishi's daily school life. Her key relationship is with Shiraishi, and she interacts primarily within that friend group.

The character has no notable abilities or special skills highlighted in the series. Her development is minimal; she remains a consistent supporting character who helps round out Shiraishi's world without undergoing any significant personal growth or change. Overall, Miyo is a minor friend character whose function is to support the main cast rather than drive the narrative.