Wikisimpsons - The Simpsons Wiki
Kumiko came to Springfield when she was touring around America's saddest towns and cities. She walked past Comic Book Guy's shop and saw him through the window and liked him. She came into the Android's Dungeon to purchase a copy of New Radioactive Man#1 and revealed to Comic Book Guy that she liked to draw manga and was drawing her life up, showing Comic Book Guy a panel in her comic, Coming-Of-Age Sad Happy Book. Comic Book Guy then gives her flowers in a Hulk hand.
Comic Book Guy and Kumiko go on a date to Chuck Dukewagon's All American Chow Lounge where Comic Book Guy can't help but insult the restaurant, and Kumiko gives her blessing for him to do so, as she likes it. After this, Comic Book Guy realizes that he is in love. They then go on several more dates and attended Bi-Mon-Sci-Fi-Con together. Eventually, Kumiko decides to move into Comic Book Guy's basement with him.
When Homer went to take Kumiko and Comic Book Guy a housewarming gift, Homer bumped into Kumiko's father, and Homer accidentally badmouthed Comic Book Guy, resulting in Kumiko's father taking Kumiko away again. Homer went to set things straight with him, taking him out and getting drunk together on Snake Rice Wine and hallucinating. Kumiko's father has an epiphany during this time and gives his blessing for Kumiko and Comic Book Guy to be together.
The Simpsons: Tapped Out
Behind the Laughter
In The Simpsons: Tapped Out "What Animated Women Want" episode tie-in, Comic Book Guy says "A new sushi restaurant? Well, I don't have a Japanese girlfriend yet -- SPOILER ALERT! -- but I may as well prime my palate.", referencing Kumiko and the storyline, 9 months before it aired.
Kumiko made her first appearance in The Simpsons: Tapped Out, before her appearance in the show. She is the first character to have made her first appearance in Tapped Out, the second being Freedom.