Ayumi Kudou serves as a waitress at the café Milkyway. She stands between 165-166 cm tall, possessing brown eyes and brown hair extending to her waist. Her physical measurements are documented as approximately 82-54-84 cm or 86-55-87 cm. Depictions sometimes include her wearing glasses and a scarf.

Ayumi is established as the childhood friend of Akira and sister to Kenji Nanase. She begins working at Milkyway to support Kenji during financial hardship, a decision that creates tension with Akira. Ayumi later enters an affair with Kenji, resulting in the birth of their daughter, Yuuri Kudou. Yuuri becomes a central figure in Milkyway 3.

Her name, 工藤 亜由美 (Kudou Ayumi), carries specific meanings: "工" (worker), "藤" (wisteria), "亜" (inferior), "由" (reason), and "美" (beauty).

Ayumi features as the protagonist in *Ichigo-da* and *Milkyway 1.8*. She also appears as a side character in *Milkyway 2* and *Teriru no Christmas BOX*.