Kintokimame are red kidney beans in sweet syrup. It is a small side dish that is often in the corner of a bento box. Because of its very sweet flavor, Kintokimame is not exactly a dish that goes well with Steamed Rice directly, which almost always comes with Japanese meals; however, it is a great pallet cleanser between rice and salty dishes.
Kuromame are Japanese black beans cooked in sweet syrup. It is a part of Osechi Ryori, the traditional Japanese new year feast. There are a lot of kinds of dishes for Osechi, but Kuromame is one of the big three celebration dishes, along with Tazukuri (candied dried anchovies) and Kazunoko (herring roe). Sweet Kuromame is a nice complement to a lot of the other saltier dishes in Osechi.