This character, Rumiko Fujikawa, was introduced to Tony Stark (and to the readers of Marvel's Iron Man comic book) in the May, 1998 issue (Iron Man Vol. 3 No. 4). Note the "Piyo Piyo" shirt.
The story was written by Kurt Busiek and drawn by Sean Chen. Busiek is well known among fans of the American superhero-comics genre. He is also an avowed fan of Rumiko Takahashi and has cited Maison Ikkoku and One Pound Gospel as his favorites among Takahashi's works.
Rumiko Fujikawa reappeared in later Iron Man stories, and had a brief affair with Tony Stark (naturally). As far as I know, she has only worn the "Piyo Piyo" shirt in issues 4 and 5. Unfortunately, I just never liked the character much, although I really wanted to, given the way she was introduced...