Asaka Kaitani is a villainess of Vampire Legend Case. She was a boutique store owner and one of the guests at the "Ruins" boardhouse and hotel visited by Hajime Kindaichi and his friends.
Asaka's backstory revealed her as a greedy villainess and an accomplice to Ikuo Futagami the doctor. Prior to being a boutique store owner, Asaka was a nurse working at the hospital at the village alongside Ikuo and the young doctor Keisuke Hiiro, with Yuria Tsuji the young and beautiful daughter of a hotel owner (the former location of the boardhouse), as well as Keisuke's lover, being a recurring patient due to her frail body. One day, a young girl was heavily injured in a accident and was admitted to the hospital, with Ikuo being the head doctor who performed her surgery. However, the surgery ran into a problem as the girl possessed the extremely rare Bombay blood type, which cannot accepts any other type except its own. Taking an advantage of the situation, Ikuo and Asaka concocted a plan and made an offer to the girl's father to get the required blood in exchange for 50 millions yen, with the girl's father agreed as he had already lost one of his daughter when she was still an infant. The two later approached Keisuke and Yuria also possess this blood type and asked the former to donate his blood to the girl, which Keisuke agreed. Despite that, Keisuke's blood was still not sufficient for the operation. Hearing this, the selfless Yuria offered to donate all her blood to save the girl, knowing that she had only six more months to live. Though both Ikuko and Asaka were reluctant at first, they eventually agreed to Yuria's request and saved the girl at the price of Yuria's life. Fearing that their monetary deal might be exposed to the media, the two concocted an event to make it seems that Yuria was killed by a vampire and drained of all her blood (with Ikuo dressing as a vampire and Asaka pretending to be a hynotized Yuria) to scare away the villagers and the police, much to Keisuke's disgust and despair. Asaka and her partner-in-crime Ikuo later repeatedly visited the now abandoned hospital to prevent any person from investigation the case, with their goal was to conceal the secret forever.
Unexpectedly for Asaka, she was captured alongside Hajime's friend Miyuki Nanase on the day of his visit and shortly later, strangled to death by Aoko Minato, the vengeful younger half-sister of Yuria who came to take revenge on her for (indirectly) being responsible for her sister death and covering it up for their selfish gain. After Asaka was murdered with the captivated Miyuki as a witness, Aoko proceeded to drain large amount of blood out of Asaka and transported her body and later Miyuki from the basement to Asaka's room in order to create an alibi for herself, later dumping Asaka's blood inside the women's bath in order to create a vampiric scene to mimic the legend. Aoko was later exposed by Hajime as Asaka and later, Ikuo's murderer, with the villainess' misdeed being revealed posthumously.
- In the anime, Asaka's role was instead replaced by the male nurse Masao Kaitani and Ikuko Futagami (Ikuo's replacement) due to the change in the storyline, with Ikuko murdered in the same way as her and Masao was not murdered by Aoko in the anime due to Keisuke's intervention.
- Asaka was portrayed by actress Yorie Yamashita in the series' drama adaptation.