This cow temple is special. This cow must have been very important to have an entire temple dedicated to it.
This cow is special because it belonged to Tokugawa (とく) Ieyasu, the first shōgun of the Tokugawa shogunate and uniter of Japan! He's a super important figure in Japanese history. You should absolutely look him up and read a bit about him (when you're caught up on these lessons, that is).