Age: 30
BWH: 34-23-34 (86-59-87 in centimeters)
Nationality: Half-Japanese, Half-English

Yomiko is a bespectacled substitute teacher and an introvert. A bibliophile, she prefers to bury herself in her books. She spends almost all of her income on books, and she lives in an apartment that is entirely stacked floor to ceiling with books. She resides somewhere in Jinbōchō, a neighborhood of Chiyoda, Tokyo known for its large amount of used bookstores.

She is also a secret field agent for the British Library. She is a Papermaster, a person with the ability to bend paper material to her will. She can make paper bulletproof or sharper than the sharpest sword. If she has enough paper, then she can construct a giant paper airplane that flies. The only limit to the effects she can create is her own imagination. It seems that she must have in her grasp of at least hands, teeth, or perhaps some other body part at least one piece of paper in order to use her powers, though eventually by the time of R.O.D the TV she appears to be able to manipulate paper by pure mental control.

Yomiko's code name for the British Library is "The Paper" (sometimes in English dubs referred to as "Agent Paper" or "Miss Paper"), and she is the 19th person to serve the Library in this capacity. Yomiko often embarks on dangerous missions assigned by her director, known only as "Mr. Joker". Because of her social awkwardness and occasional clumsiness, she would not seem to make a very good secret agent, and many times she allows her emotions to get in the way of defeating an enemy. However, if receiving the proper support (she is often paired with focused, effective agents like American mercenary Drake Anderson), she can actually be quite useful, with ninja-like reflexes and sharp wits in combat. She is considered one of the Library's top agents.