Necessity is the mother of invention, as they say. But for grandmother Yoko Sukekawa, it's the inconveniences she encounters in her daily life that get her inventor's juices flowing.

"I don't think there's anything I'm fully satisfied with," says the 67-year-old Tokyo resident who has been inventing things for more than a decade. "But whenever I spot some inconvenience, I feel lucky because there's the fun of overcoming it," she says, cheerfully.

In fact, Sukekawa's inventions, or original ideas, are mainly items that make her everyday chores easier and more enjoyable. And the ideas usually start off with something she wants for herself.

For example, because she always found it cumbersome to carry an umbrella when shopping, Sukekawa designed and made an original nylon bag with a special umbrella pocket that could be concealed when not in use. Another time, when arm pain made it difficult to pick things up, she made a dishwashing glove shaped like a round mitten that makes it easier to handle dishes. She spun this into a similarly shaped dusting cloth made of faux chamois.

These are just a few of Sukekawa's inventions sold at Keio Department Store in Tokyo's Shinjuku district. In the section called Naruhodo (Oh, I See) Corner, selected inventions by members of the Japan Women Inventors Association have been marketed for nearly 40 years. Sukekawa, who joined the group more than 10 years ago, now has eight of her original products on display there among nearly 200 in total from association members.

Among the most popular items Sukekawa sells are plastic partitions that allow folded clothes to be stored vertically in drawers. Her self-avowed masterpiece, though, is her Maki Maki Shuno -- a pipe-shaped device that allows you to roll up and squeeze the air out of down-filled futons in just a couple of minutes, then store them compactly in a bag incorporated into the pipe. "I always wanted to secure more space in the closet, and futons used to take up such a lot of room," Sukekawa explains.

Though she may have been aware of the futon problem for a long time, Sukekawa says that she never sits down at her desk and pulls her hair out searching for a solution. Instead, she says, ideas often come to her when she is doing other things. In the case of her futon device, she says that she's had some paper pipes in her house for a few years, then suddenly she visualized how to use them and immediately made a prototype. "Inventions are not created in your head but in your hands," Sukekawa says.

Since her Maki Maki Shuno -- which is now made in a small factory in Ibaraki Prefecture -- came out four years ago, Sukekawa has sold about 5,000 of them, at 2,800 yen each. Though not all her inventions sell that well, any profits, no matter how small, get plowed back into developing her next idea.

"Some people are too focused on selling their inventions and making money, but I don't think things will go well if you are too eager, because you can become upset and try even harder and then end up losing more money," Sukekawa says. "I don't care if my inventions don't sell, because I really have fun coming up with ideas and enjoy the creative process."

Though Sukekawa says that as a child she was always making things, her life as an inventor didn't begin until after she turned 50. Before that, Sukekawa had been a physical education teacher at junior and senior high schools in Aomori Prefecture. After developing a serious medical problem, she quit her job and moved to Tokyo with her husband to receive treatment. As she had no friends in Tokyo, her daughter gave her the names of some amateur inventor groups she thought her mother might enjoy as a hobby and as a way to meet people.

Enjoy she did. Sukekawa eventually entered invention contests and won prizes. Then she gravitated naturally to the JWIA, which gave her more opportunities to display her inventions. Also, the other inventors gave her advice on how to make and sell her products. Without their help, she says she would never have thought of marketing her products.

"Since I always come up with something I want for my own use, I don't care if it's just one item. But if some people are encountering similar inconveniences in their lives, and my inventions can solve their problems, that makes me really happy," she says.

Interestingly, Sukekawa believes that the rich seam of domestic inconveniences she mines is there in the first place because so many mass-produced products are designed by men -- men who, by and large, don't use the products themselves. And people just adjust to using poorly designed products.

Although she concedes that things are changing slowly, as more companies solicit consumers' views or use focus groups to assess new products, Sukekawa says this doesn't stop ideas from endlessly popping into her head. From October, in fact, the fruit of another of Sukekawa's brainwaves will take its place in Naruhodo Corner. A multipurpose container, this is a revised version of one of her inventions that won a prize in a JWIA contest held in the Keio Department Store.

"Through inventions, I receive happiness, pleasure and hope from many people," Sukekawa says. "That's why I can't quit."