If you're spending some time in Koniya, Amami Gunto National Park and Kochiyama Observatory are top sights worth seeing.
While Sumiyoshicho might not have many sights to explore, venturing just a little farther will lead you to top things to see and do like Kagoshima City Aquarium and Sakurajima Port Ferry Terminal.
If you're spending some time in Chiranchokori, Chiran Peace Museum and Satsuma Denshōkan are top sights worth seeing.
Nishikomi might not have many top sights, but Sanekukai Beach and Yakiuchi Bay are two attractions nearby that you can check out.