Antique Japanese Cast Iron Teapot or "Tetsubin".

From my understanding, this is an antique Japanese cast iron tea kettle. This one has a "hado" or sanded exterior. I learned that many earlier artists formed theirs as such, with major differences being the color variation and style. The color of this cast iron kettle looks like bronze, its a very beautiful cast iron look. The elements, which were combined like a recipe, and most likely handed down, or from local available minerals, were used in the cast molds to produce no more than one or two pots at a time. At this point a new mold would be created for another new pot. Later dignified clientele started requesting customized kettles with decorative molds. Some were of animals, other's scenery molds, ect. Due to the recent demand in everything Asian, these antique cast iron pots are becoming trendy. Many like the antique or artistic qualities, some prefer to use cast iron kettles for the flavor of waters produced by them. Even new manufacturers are reproducing such kettles, to meet demands at a more affordable cost. With that being said I don't think new suppliers can take away from the unique appreciation that these older more cherished kettles have to offer. The color, along with the bronze copper lid that takes on sort of a plum color, which plays into the bronzy hue happening here. The mystery in this Tetsubin is primarily "who" made it? Since it's signed, it may not be too hard to figure out, however, I have no clue what the signature means, or have I found a kettle with this artists signature yet. Hoping to attract someone here that can tell me what these symbols mean. Please refer to pictures above. Thanks so much for looking.