Ryoko Nishizuka graduated from Musashino Art University in 1995, and began working as a graphic designer at a design studio, but her main interest was always in typeface design. In 1997, Ryoko joined Adobe. She was involved in the development of the Kozuka Mincho and Kozuka Gothic typefaces designed by Masahiko Kozuka. In 1999, Ryoko received an honorable mention for her typeface Branch Letter at the Morisawa Awards International Typeface Design Competition.

In 2002, her calligraphic typeface Teika won the Silver Prize at the same Morisawa competition, which was later expanded and refined to become Kazuraki and heralded as the first fully-proportional OpenType Japanese font. In 2003, Ryoko created the Ryo Text and Ryo Display kana typeface families, followed by the Ryo Gothic family in 2004. Kazuraki then consumed much of Ryoko’s effort to overcome various design difficulties, and was subsequently released for the first time in 2009. The special glyph set for Kazuraki, including proportional glyphs and ligatures, was expanded, and the font was updated in 2010.

In 2014, as a co-development project with Google, Ryoko directed the design work for Source Han Sans, Adobe’s first Pan-CJK typeface family comprising seven weights. Each Source Han Sans font includes more than 64,000 glyphs to support Simplified Chinese, Traditional Chinese, Japanese, and Korean scripts. In 2017, she also directed the design work for Source Han Serif, which became Adobe’s second Pan-CJK typeface design. Traditional and modern styles are incorporated into the designs of these Pan-CJK fonts, and it makes text clearer and more readable on smaller devices such as tablets and smartphones.

Also in 2017, she designed Ten Mincho. Prominent in this design are the dynamic characteristics of hand-written characters, as well as a stroke formation style that is typically seen in the Kawaraban printed newspapers from the mid-to-late Edo period (1603–1863) in Japan.