In Japanese it's a combination of two words. The 'da' part refers to a field, particularly a rice paddy, and the first part of the surname refers to the position that the person occupies in that field and hence their social status. There are many other examples of surnames ending in 'da'
Yoshida, Yamada, Toyoda, Genda, Fukuda and so on. I'm not sure about Yoda though.
The Japanese word 'Ton' means 'pig' or 'pork' , apparently.