|Occupation(s)||school counselor, computer programmer|
|Manga Debut||Chapter Six: We have a problem, big sis|
Riko Onizuka (鬼塚 理子, Onizuka Riko) is the 30-year-old supporting character in Dengeki Daisy. She works as school counselor at Teru Kurebayashi's high school. She was a former member of the design team Soichiro led. As a result, she regards Teru as a younger sister and they live together as housemates and Tasuku Kurosaki's neighbors. Riko is friends with Kurosaki and often subtly serves as his adviser on his situation with Teru, frequently teasing him or acting violently toward him if she thinks he has acted inappropriately towards Teru.
Riko appears to be dark haired, and usually wears her professional work clothes. She's sometimes shown to be smoking a cigarette behind the school building, and people occasionally make jokes about how she's getting older. Despite comments about her age, she is considered to be an attractive woman. Teru particularly admires Riko's height and figure, which Riko states includes that she has D-cup sized breasts.
Riko is often depicted as a compassionate and mature woman, who dispenses advice with tact and subtlety to her friends and students. She is particularly close to Teru, whom she sees as a younger sister, and frequently takes a leadership role within the group supporting Kurosaki and Teru. She is kind and generous towards most people, and often acts as a voice of reason and restraint towards the more extreme attitudes of Kazumasa Andou or Master Masuda.
Though Riko is usually composed and confident, she actually has a short temper and does not hesitate to physically reprimand her male colleagues, though she is fully capable of holding her temper in check around her students. While possessing great sensitivity towards others, Riko keeps her own feelings of sadness and guilt towards Soichiro's death to herself. However, she sincerely wishes for Kurosaki's happiness and supports his relationship with Teru, despite teasing and acting violently toward him for perceived inappropriate behavior.
Along with Kurosaki, Riko was part of a team of engineers led by Soichiro Kurebayashi at Kenbashi Electronics, a rising engineering firm. During her time at Kenbashi Electronics, Riko met Kurosaki, Master Masuda, and Kazumasa Andou.
It is unknown what she did after Soichiro died until the point when she was hired to become the school counselor at Teru's school. It is implied that Riko is connected with a number of local engineering firms, given her offer to find Kurosaki a suitable job away from Teru, and it is known that she does part-time for some old colleagues. She has a background studying psychology, which allowed her to eventually become the counselor at Teru's school.
Riko is the girlfriend of Soichiro Kurebayashi, who assumed to be in a long term relationship. It is also mentioned that they had intended to get married some day, though Soichiro said that he can not get married until his younger sister gets a husband.