No need for any secret tricks or seasoning! It's an inexpensive and delicious shiro-an (white sweet bean paste) that you'll just have to try.
I love shiro-an. My mother-in-law taught me this quick and easy recipe for the New Year's feast. When I tried it, it was so delicious that I finished the whole batch in just a few seconds.
Don't mash the beans too much if you want to keep a slightly chunky texture.
Enjoy Japanese food around the world.