Iron tsuba signed "Kitagawa Zengoro Akihide". I was not able to find any information about this craftsman, other than one example of tsuba signed with this name on Japanese dealers website:
Kitagawa Zengoro is a name of first Soten School master. Some of his students also took the name "Zengoro" and they belonged to Kitagawa family. Therefore there where few Soten School members named Kitagawa Zengoro. However I could not find any named "Akihide".
There is also a possibility that it is signed "Munehide", kanji for "Aki" and "Mune" are slightly different but if written poorly could look similar. This would be a simpler explanation as Munehide was a student of first generation Soten School master and he was also called "Zengoro". So he could sign Kitagawa Zengoro Munehide.
Either way I do not have enough information to guarantee the authenticity of signature on this tsuba.
This tsuba is slightly different than standard Soten tsuba. There are no sukashi other then hitsu-ana and mimi is decorated with carved waves and inlaid droplets.