If you're looking for some top things to see and do in Central and surrounding area, you can visit Maizuru Castle and Yamanashi Prefectural Office.
While there might not be top attractions in Midorigaoka, you can explore the larger area and discover places like Hosen-ji Temple and Takeda Shrine.
When in Kokubo, you can plan a visit to Yamanashi Prefectural Museum of Art and Yamanashi Prefectural Office, some noteworthy sights in the nearby area.
While visiting Yumura, you might make a stop by sights like Chichibu Tama Kai National Park and Entakuji Temple.
If you're spending some time in Kitaguchi, Sadoya Winery and Kofu Fujimura Memorial are top sights worth seeing.