We call this "spinning juji;" I have learned this drill at a camp from Steve Scott.

There are a couple of finer points missing from this video:

When tori spins, he should be shrimping on his right side. His right leg should be higher, on uke's shoulder blade, and tori's right foot should be pointed in the direction he is going to roll. Tori should remain rounder as he rolls up. For the finish, he should "fall" on his side toward uke's head, then make an arc with his body to extend uke's arm.