This is a set of Gakken New Block Shinkansen Bag, purchased a few years ago, containing 15 types and 66 parts, plus additional parts, for a total of 99 parts. It's a set that can be used to build robots and Shinkansen trains, as shown in the last image. However, it seems there's only one rectangular prism, and some parts may be missing from the original set. I hope you can use it in combination with what you already have.