As an honorific second-person pronoun

Otaku is derived from a Japanese term for another's house or family ( otaku) that is also used as an honorific second-person pronoun. The modern slang form, which is distinguished from the older usage by being written only in hiragana (おたく) or katakana (オタク or, less frequently, ヲタク), or rarely in rōmaji, appeared in the 1980s. In the anime Macross, first aired in 1982, the term was used by Lynn Minmay as an honorific term.オタク市場の研究(Otaku Shijou no Kenkyuu), 野村總合研究所(Nomura Research Institude), ISBN 978-986-124-768-7 It appears to have been coined by the humorist and essayist Akio Nakamori

From the works of science fiction author Motoko Arai

Another source for the term comes from the works of science fiction author Motoko Arai. In his book Wrong about Japan, Peter Carey interviews the novelist, artist and Gundam chronicler Yuka Minakawa. She reveals that Arai used the word in her novels as a second-person pronoun, and the readers adopted the term for themselves.

In Japan

In modern Japanese slang, the term otaku refers to a fan of any particular theme, topic, or hobby. Common uses are anime otaku (a fan of anime ), cosplay otaku and manga otaku (a fan of Japanese comic books), pasokon otaku (personal computer geeks), gēmu otaku (playing video games), and wota (pronounced 'ota', previously referred to as "idol otaku") that are extreme fans of idols, heavily promoted singing girls. There are also tetsudō otaku or denshamania (railfans) or gunji otaku (military geeks).

While these are the most common uses, the word can be applied to anything (music otaku, martial arts otaku, cooking otaku, etc).

The loan-words maniakku or mania (from the English "maniac" and "mania") are sometimes used in relation to specialist hobbies and interests. They can indicate someone with otaku leanings, (for example- Gundam Mania would describe a person who is very interested in the anime series Gundam). They can also describe the focus of such interests (a maniakku gēmu would be a particularly underground or eccentric game appealing primarily to otaku). The nuance of maniakku in Japanese is softer and less likely to cause offense than otaku.

Some of Japan's otaku use the term to describe themselves and their friends semi-humorously, accepting their position as fans, and some even use the term proudly, attempting to reclaim it from its negative connotations. In general colloquial usage however, most Japanese would consider it undesirable to be described in a serious fashion as "otaku"; many even consider it to be a genuine insult.