Sightseeing>Seasons>Expo 70 park
Expo ’70 Commemorative Park
Amazingly vast area has several museums and gardens. You can enjoy through the year to enjoy flowers.
You definitely find favorite garden out of many different types of gardens.
Good thing about this plce is that the admission fee is cheap.
Expo '70 park website: http://www.expo70.or.jp/e/
My recommendation is National Museum of Ethnology, Osaka Japan. You need more than a day to see all the displays.