She is a young researcher in her mid20039s who is also Professor Kakuzawa039s partner who works alongside him to create a vaccine in order to counter the threat of the Diclonius virus. She along with Kohta inadvertently discovered Professor Kakuzawa039s severed head and warned the boy not to disclose anything of what he saw or heard with anybody else. Afterwards she reported her finding to Director Kakuzawa at his compound facility but he wouldn039t let her go scotfree after seeing his son039s horns. She was threatened by Chief Kakuzawa to take charge of his deceased son039s research or else be killed. In the anime Arakawa is a minor character whose role provides little or no contribution at all for advancing the plot as later she039s often seen complaining about that being so busy does not allows her to take a shower which becomes a recurrent gag in the series. In the manga she plays a much more pivotal role and her personality is much more jaded. Source:wikipedia