An Actress for the Ages : She’s Grandma on ‘All-American Girl,’ but Amy Hill takes an even bigger age leap by playing her own 80-year-old mother on the stage.

Amy Hill isn’t as old as she might appear. Not by a long shot.

“A lot of people think I’m just an obscure old actress,” says the versatile Hill, 41, who plays Margaret Cho’s 65-year-old grandmother on the ABC comedy series “All-American Girl.” Although the show is reportedly undergoing major retooling for next season, Hill is confident that her character will survive the transition. “Grandma seems to be one of those characters that people of all ages relate to,” she says earnestly. “Kids love me. And grandmothers really love me.”

In her newest incarnation, Hill stretches the time warp even further, playing her own 80-year-old mother, Ayako Yoneoka Hill, in “Reunion” at Theatre Geo in Hollywood. The solo piece--which Hill wrote and which she swears will be her last autobiographical stage turn--marks the final entry in a trilogy that began with the recollection of her teen-age excursion to her mother’s homeland in “Tokyo Bound” (1991) and more childhood memories in “Beside Myself” (1992).

In “Reunion” (originally presented in different form in 1993 for two performances at the Japan America Theatre and a single performance in the L.A. Festival), Hill affects her mother’s charmingly fractured speech to tell the story of her life from childhood to current time, revealing along the way a woman with a sweetly eccentric personality and a survivor’s grit.

“She was born in Kumamoto, on the island of Kyushu in Japan,” Hill says. “Her mother passed away from tuberculosis when she was 4, and her father remarried--to a really mean woman. It was a very poor time for them. I think she always felt she wanted more as a woman, that she was oppressed by the limits there. When she got older, she rebelled against her family by marrying someone they didn’t want her to marry--and then rebelled against her husband’s family and the pattern her life was supposed to take.”

After her first husband was declared missing in action in World War II and presumed dead, Hill’s mother married an American soldier--only to have her first husband reappear. She and husband No. 2 quickly left Japan and settled in Deadwood, S.D. (the home base of Hill’s Finnish American paternal grandparents), and later Seattle, where they raised three children.

Her mother (who now shares a duplex in San Francisco with Hill’s younger sister) was in the front row when “Reunion” had a single performance last May at Highways in Santa Monica.

“When embarrassing stuff came up, she was happy,” reports the actress, who had gathered the biographical anecdotes in a series of taped interviews with her mother. “When I first started writing, she’d call me up and say, ‘You’ve got to put in this story and this story.’ At this stage in her life, she doesn’t care who knows. Although she was confused why people laughed at the part about (her initially exuberant involvement with) Jehovah’s Witnesses, she knows other parts are funny.”

Hill stresses that she’s been selective--and protective--in the stories she shares.

“With my mother, it’s always been a journey of searching, of moving to independence and self-reliance,” says the Silver Lake-based Hill, who has successfully toured “Tokyo Bound” and “Beside Myself” to college and theaters across the country. “People may perceive some of what I bring up as being in bad taste. But I do it to give a sense of the horror she lived with and how it impacted her, how she holds life dear.” Hill’s voice softens. “I like her ability to allow her fantasies to exist. She’s always had that.”

Another constant about her mom, the performer says, is that she “has always been so supportive of me.” Hill traces her interest in acting to a school field trip that introduced her to the Seattle Repertory Theatre. After high school, she was accepted at Sophia International University in Tokyo and spent the next six years in Japan, where she parlayed her interest in drama and her bilingual skills into work as a TV and radio broadcaster. When she returned to the States (with her Japanese husband, whom she later divorced), Hill trained at American Conservatory Theatre in San Francisco and went to work on an acting career, moving to Los Angeles in 1986. Her film credits include “Dim Sum,” “Singles” and “Rising Sun.”

T hrough it all, and especially in her writing, family ties have been important. Hill has a sister who is a travel agent, a brother who is a cultural diversity consultant. The actress says that the death of her then-husband’s mother in Japan “gave me a sense of preciousness about my parents. I said a lot of the things I wanted to say. So when my father passed away (10 years ago), there was a sense of completion.” Nowadays she sees her mother every couple of months and talks to her on the phone often.

The actress says she has been fiddling with improvisation on her mother’s character for a long time. Even Grandma on “All-American Girl” was created with her mother in mind.

“I’ve known Margaret Cho for years,” Hill explains. “Originally, we developed the show with me in the role of Margaret’s mother. But then they couldn’t find someone to play Grandma, so they shifted me over to the grandmother role--and I’m glad because there’s more range; she’s a more interesting character. Also, when people respond to her, it validates my mother, because I based the character on her.”

“Reunion” director Anne Etue has been friends with Hill for six years and directed both of her previous solo shows. “We have similar insights about life and humor,” Etue notes. Backgrounds too: Although they never met while growing up, both were raised in Seattle and both attended the University of Washington. And then there are their mothers.

“Amy’s mother was a war bride,” Etue points out. “And my mother was in the nurse corps in Gen. Patton’s army, was captured by the Nazis and went on to raise 10 children.” Etue and Hill even created a cable series, “Mrs. Hill and Mudd” (1990-92), based on--what else?--their mothers.

In spite of the very personal nature of “Reunion,” Hill is quick to resist the word tribute .

“I don’t want my mother to seem perfect,” she says firmly. “And beyond telling her story, I wanted to tell a larger story. It’s a celebration of who we are, all women. When I did this in Canada (for the 1994 Montreal Fringe Festival), so many women came out of the show and said, ‘That’s my mother.’ ‘That’s my situation.’ ‘Maybe that’s what we’ll be like when we’re 80.’ My hope is that people walking away feel that they got to know this woman and maybe also know the women in their lives.”

And the adventure continues. Hill--who has been juggling a 9-to-5 schedule on “All-American Girl,” teaching playwriting at East West Players, performing in local benefits and writing for the new PBS children’s show “The Puzzle Place”--emphasizes that mother-daughter relations are never dull.

“The older she gets, the funnier she is,” the actress says. “But she’s always been extremely interfering. And we’re both very honest and blunt with each other. Every day, she still makes me crazy.”*

* “Reunion,” Theatre Geo, 1229 N. Highland Ave., Hollywood. Fridays and Saturdays, 8 p.m.; Sundays, 2 and 8 p.m. Ends May 14. $20; students and senior citizens, $15. (213) 660-TKTS.