Perhaps the best known of the first-person pronouns is watakusi, which sounds a bit stiff unless shortened to watasi. Other common contractions are atakusi and atasi. The latter is usually thought to be limited to women's speech, and when the use is deliberate (as in writing) atasi will probably be a reference by a female to herself; but in rapid speech men may unconsciously use the same form as an abbreviation. Examples can be found in transripts of the speech of Tokugawa Musei.
Бесценная грамматика Сэмюэля Мартина, стр. 1076. Вот теперь "атаси" Кёна, вроде как мелькнувшее в одной из серий "Меланхолии Харухи Судзумии" и несказанно меня поразившее, уже не удивляет. И:
The pronoun boku is the first-person pronoun preferred by most males under neutral circumstances, though they will replace it by wata[ku]si in formal situations. Boku, a Chinese loanword for 'slave', gained popularity in Meiji days as student slang for '[Your] Servant=I/me' ("впк" по-нашенски - a_c), and for years it has carried a masculine aura that is still strong, though it is now said to be in use among college girls.
Та же страница.
Знаете, за что я люблю японский язык? "Бодрит" (с)