i usually buy japanese snucks or ramen from the Duty free stores at the airport when i go oversee. And beautiful chopsticks would be good too. And for people live in could area, i buy "Heat-Tech Shirt" from UNIQLO!
If you don't have much budget for souvenir, why don't you try to go 100 yen shops (Daiso, Cando, Serlia...etc). Even it is just 100yen, there are tons of variation of goods. Among them, I often buy chopsticks, cute japanese last design coasters, maccha (green tea) taste chocolate / candies, tenugui (japanese textile). I am sure you can find some beautiful souveniors.
Karinto, Senbei are Japanese like snack and it lasts for long time. But everyone may not like them.
How about Japanese wine, sake.
As some brands come in very nice bottles, so you can enjoy the alcohol and have a nice keepsake afterwards.