Arudou was born David Christopher Aldwinckle in California in 1965. He attended Cornell University, first visiting Japan as a tourist on invitation from , his pen pal and future wife, for several weeks in 1986. Following this experience, he dedicated his senior year as an undergraduate to studying Japanese, graduating in 1987. Aldwinckle moved to Japan and taught English in Sapporo, Hokkaidō, for one year, then decided to return to university in the United States to study. He entered the Graduate School of International Relations and Pacific Studies (IR/PS) at the University of California, San Diego (UCSD), but deferred from the program in order to return to Japan and spent one year at the Japan Management Academy in Nagaoka, Niigata Prefecture. Aldwinckle married Ayako Sugawara in 1989. In 1990, he returned to California to complete his Masters of Public and International Affairs (MPIA), and received the degree in 1991.
Aldwinckle then joined a small Japanese trading company in Sapporo. It was this experience, he recounts, that started him down the path of the controversial activist that he would later become. "This was a watershed in my life," Arudou writes. "… and it polarized my views about how I should live it. Although working [in Japan] made my Japanese really good — answering phones and talking to nasty, racist, and bloody-minded construction workers from nine to six — there was hell to pay every single day." Arudou contends that he was the object of racial harassment. Aldwinckle quit the company. In 1993 he joined the faculty of Business Administration and Information Science at the Hokkaido Information University, a private university in Ebetsu, Hokkaidō, teaching courses in English as a foreign language. As of 2007, he is an associate professor.
Arudou and his wife divorced in September 2006. Following their divorce, Arudou petitioned the Sapporo Family Court to have his ex-wife’s family name, "Sugawara" removed from his koseki. The court granted the request and his name was officially changed to Arudou Debito in November 2006.
Arudou was one of three plaintiffs in a racial discrimination lawsuit against the Yunohana Onsen in Otaru, Hokkaidō. Yunohana maintained a policy to exclude non-Japanese patrons; the business stated that it implemented the policy after Russian sailors scared away patrons from one of its other facilities. After reading an e-mail posted to a mailing list digest complaining of Yunohana's policy in 1999, Arudou visited the hot spring (onsen), along with a small group of Japanese, White, and East Asian friends, in order to confirm that only visibly non-Japanese people were excluded.
Arudou assumed that when he returned in 2000 as a naturalized Japanese citizen, he would not be refused. The manager accepted that Arudou was a Japanese national but refused entry on the grounds that his foreign appearance could cause existing Japanese customers to assume the onsen was admitting foreigners, i.e drunk Russian sailors which were causing problems in that locality, and take their business elsewhere.
Arudou and two co-plaintiffs, Kenneth Lee Sutherland and Olaf Karthaus, in February 2001 then sued Yunohana on the grounds of racial discrimination, and the City of Otaru for violation of the United Nations Convention on the Elimination of All Forms of Racial Discrimination, a treaty which Japan ratified in 1996. On November 11, 2002, the Sapporo District Court ordered Yunohana to pay the plaintiffs 1 million JPY each (about $25,000 United States dollars in total) in damages. The court stated that "refusing all foreigners without exception is 'unrational discrimination' [that] can be said to go beyond permissible societal limits." The Sapporo High Court dismissed Arudou's claim against the city of Otaru for failing to create an anti-discrimination ordinance; the court ruled that the claim did not have merit. The Sapporo High Court upheld these rulings on September 16, 2004 and the Supreme Court of Japan denied review on April 7, 2005.
In February 2007, Arudou protested against the book Kyōgaku no Gaijin Hanzai Ura File - Gaijin Hanzai Hakusho 2007 (Secret Foreigner Crime Files). Arudou posted a bilingual letter for readers to take to FamilyMart stores protesting against "discriminatory statements and images about non-Japanese residents of Japan."
In June 2008, Arudou lodged a complaint with the Hokkaidō Prefectural Police, claiming that its officers were targeting foreigners as part of a security sweep prior to the 34th G8 summit in Tōyako, Hokkaidō. This followed an incident in which Arudou refused to show identification when requested by a police officer at New Chitose Airport. After meeting with police representatives at their headquarters, Arudou held a press conference, which he described as the "third-best press conference I’ve ever done". The press conference was covered by a local television station.
Arudou maintains an active online profile In her review of Japanese Only (see "Publications" below), Yuki Honjo praised Arudou's "comprehensive website with thousands of pages of material" as an "excellent resource". Nevertheless, Honjo noted that "Arudou's brand of 'Internet activism'... seems almost quaint" and his lack of engagement with more contemporary protest methods, such as flash mobs, blogs or wikis, essentially means "he remains the old-fashioned pamphleteer." Arudou has since set up a blog where he comments on an almost daily basis.
Alex Kerr, author of the book Dogs and Demons has criticised Arudou for his "openly combative attitude", an approach that Kerr thinks usually "fails" in Japan and may reinforce the conservative belief "that gaijin are difficult to deal with". Nevertheless, he comments that "perhaps we who live here are slow to stick our necks out...and quick to self-censor...to get along....". He also sees Arudou's decision to naturalise as bringing "the dialogue inside Japan. His activities reveal the fact that gaijin and their gaijin ways are now a part of the fabric of Japan's new society.
Arudou has written a book about the 1999 Otaru hot springs incident. Arudou originally wrote the book in Japanese; the English version, (ISBN 4-7503-2005-6), was published in 2004 and revised in 2006. The book is listed in the Japan Policy Research Institute's recommended library on Japan. Jeff Kingston (Temple University Japan), in a review for The Japan Times, described the book as an "excellent account of his struggle against prejudice and racial discrimination. Yuki Allyson Honjo criticized "Japanese Only" on Japanreview.net. Noting her sympathy for his plight and that her co-editor Peter Scalise had vetted a draft copy, she concluded "This book does not do the thought-provoking and complex topic of racial integration and cultural tolerance justice...."
Arudou's second book was coauthored with and titled . This was a bilingual book, which provided information on visas, starting businesses, securing jobs, resolving legal problems, and planning for the future from entry into Japan to death. Donald Richie of The Japan Times said that out of the guides for new residents in Japan, Handbook was the fullest and consequently the best.
Arudou has also written pieces for the on-line academic website Japan Focus and had his work published by the Japan Policy Research Institute, which later placed his article online when it moved to a web format.
Arudou writes a guest column, "Just Be Cause", for The Japan Times. In August 2008, Arudou drew an analogy between the words "gaijin" and "nigger", arguing that the status of "gaijin" as politically incorrect was well deserved. This prompted a large reader response, with most of the published responses finding the analogy inappropriate. This process was repeated roughly one month later, when Arudou wrote another article standing by his original statement. Again, most published responses were critical of the analogy.