Hi Makiko!
Amy has such great ideas. My guess is you are a quiet person, and as you are getting older, the fact of your love of a quiet life has lead you to some isolation. The ideas Amy has to get you out and about are great. You can also consider being a volunteer at the library, if you already go there. Some libraries have a 'friends of the library' organization. That's one idea. Another is to find a local version of the Japan-America Societies and see if they have social gatherings or volunteer opportunities. I found a web site for the national association of Japan-America Societies: us-japan.org. Do you do any kind of craft? Some senior centers have craft gatherings. I started a crochet/ knitting one in my small town and it's been going strong for 2 years with a couple of periods of shut down due to covid. We are about 6 women, and it's been great fun to get to know them better.
One of the things i learned when i was a geriatric care manager was that each of us need about an hour a day of conversation to keep our brains working optimally. If you don't have folks locally to talk to, you could schedule conversations with family members in Japan. Perhaps there's a niece or grandnephew that you could catch up with. It will help you avoid dementia, and also isolation and perhaps depression.
My guess is that you'll need to stretch out of your 'comfort zone.' And if that's really hard for you, you could get a referral to a therapist and get some encouragement and coaching on how to stretch yourself into socializing. It's not easy. But you have time. If staying sharp is a priority and a concern, you might really enjoy getting out. Spring is coming. Get out there...
And feel free to ask more questions or share more about your situation.
So glad you wrote!
Jane