Mikiyo Tsuda is a Japanese manga artist and illustrator born on January 10 in Fukui Prefecture. She is known for working under two distinct pen names to separate the different genres she explores. Under her real name, Mikiyo Tsuda, she primarily creates comedy-focused shōjo manga, while she uses the alias Taishi Zaō to publish boys' love and girls' love works. She adopted this dual identity initially to keep her involvement with homosexual romance narratives private from her family, though they eventually became aware of her work regardless. Her artistic self-representation is a teddy bear wearing a red bow tie with a bell at its center. Tsuda maintains a close professional friendship with fellow manga artist Eiki Eiki, with whom she frequently collaborates and co-authors series, and their similar art styles often lead to public confusion between the two.

Tsuda made her professional debut in 1999 with the manga The Day of Revolution, serialized in the magazine Wings. The series follows a fifteen-year-old boy who discovers he has female chromosomes and subsequently undergoes a gender transition, blending shōjo and soft boys' love elements while exploring themes of sexual identity with a mix of humor and introspection. Originally conceived as a one-volume story, fan demand led to a continuation. She continued with Family Complex in 2000 before launching her most commercially successful work, Princess Princess, in 2002. The series ran in Wings until 2006 and was collected in five volumes, with a sequel titled Princess Princess + following from 2006 to 2007. The story takes place in an all-boys school where a system of hime, or princesses, selects certain male students to dress as girls for school events to provide a sense of femininity. Tsuda intentionally kept the series as a comedic story about friendship rather than an explicit boys' love narrative, as requested by her publishing magazine.

Princess Princess became a multimedia franchise and represents Tsuda's most significant presence in anime. An anime television adaptation produced by Studio Deen aired in Japan from April to June 2006. That same year, a live-action television drama titled Princess Princess D aired from June to September 2006. A visual novel video game for the PlayStation 2 based on the series was also released in October 2006. Beyond Princess Princess, many of Tsuda's other works have been adapted or received international publication. Under the Taishi Zaō name, she has written Electric Hands, Koi wa Ina Mono Myōna Mono, and Bokutachi wa Asu ni Mukatte Ikiru no da. Her collaborative works with Eiki Eiki include Color, Haru Natsu Aki Fuyu, Love DNA Double X, the ongoing series Love Stage!!, and Back Stage!!.

Thematic elements of gender presentation, cross-dressing, and fluid identity recur throughout Tsuda's body of work. The Day of Revolution directly engages with a character's gender transition, while Princess Princess uses cross-dressing as a comedic premise within an otherwise male-only environment. This thematic focus, combined with her work across both shōjo and boys' love genres, has established her as a notable creator at the intersection of these audiences. Within the manga industry, she has drawn many covers for the magazine Wings. Her works have seen commercial success internationally, with publications in German through Egmont Manga & Anime and in English through Digital Manga Publishing.