Satsumaimo-no-Yakata
Tel: +81 099-239-4865. several hundred types of sweet potato products.
Jelly Beans
Tel 099-216-8800. the only specialist english bookstore in the prefecture, with a nice second hand section as well. take the no 1 streetcar to shinyashiki and hop off, you shouldn't have too many problems from there; just follow the signs. the shop is open tuesdays through saturdays, but if you call in advance and let them know you are coming they will try their best to open it up especially for you on sundays and mondays! the store is open 10am - 7pm
Tenmonkan shopping arcade has a plethora of shops, where you can satisfy your consuming needs.