Ai Kodama is the adoptive sister of Hikaru Kodama and works as a nurse at St. Juliana Hospital. She suffers from severe heart problems requiring continuous medical treatment and frequent hospitalization, making her reliant on the hospital's care and her sister's support.

Hikaru's actions are frequently motivated by her need to secure treatment and stability for Ai. Aware, albeit ambiguously, of Hikaru's involvement in Dr. Ryuji Hirasaka's experiments, Ai misinterprets one encounter as a dream. This leads her to express a desire to "become a real woman" to Dr. Hirasaka.

Hirasaka exploits this request to advance his experiments. He devises a method to facilitate an intimate encounter between Ai and Hikaru, leveraging Ai's vulnerability and wish for maturity. He orchestrates the experience so Ai perceives it as another dream, blurring reality and illusion in her understanding of the event.

No further development or resolution of Ai's storyline beyond this experimental encounter is documented in the available information.