Hiko Yoshida is the mother of Toshi and Akiko and wife of Hideki Yoshida as seen in "Weiner of Our Discontent". She speaks English as well as Akiko but Francine apparently pretends not to understand her, being upset that she chose her own brand of hot dogs for Steve and Toshi's hot dog eating contest; which was justified as the hot dogs Francine brought were poisonous.
Stan says that he couldn't understand Toshi's parents when he talked to them about making Toshi a man in "The Magnificent Steven". They are shown speaking English, possibly meaning Stan lied, he pretended not to understand them like Francine did in, or he spoke to a different Japanese only speaking couple.
She appears in a cameo at the end of "Shallow Vows" with Toshi.
Roger and Stan take their idea for "Male Stripper Shoes" to Mr. Yoshida to get funding for their idea in "National Treasure 4: Baby Franny: She's Doing Well: The Hole Story". He agrees to bankroll their idea on the condition that they kill his wife but they find they are unable to do it. They later spot an ad for their shoes and find he has stolen their idea.
Mrs. Yoshida's determination to get Akiko and Toshi into a good college forces a confrontation with Steve and Francine in "Spelling Bee My Baby".
Hiko Yoshida is voiced by Sandra Oh.