Danzaburo can actually be quite fun. I thought that he is not good due to the freeze. But someone in another post convinced me otherwise. The link to the exact post is below.
If you want his mana freeze to be countered, it can be done so by pairing him with heroes like Poseidon, Grazul or even Gato. However, if you have other yellows, then i would suggest working on other 4* yellows. I would only do Danzaburo if I really had no other 4* yellows to work on.