The coin you have appears to be a zinc Japanese 5 or 10 sen from the year 1944. However, such a coin is quite common unfortunately and is worth less than fifty cents as it appears to be well circulated. Nonetheless, to ascertain the denomination an image of the other side should be provided.
It is Japanese, WWII era. The "大日本" translates roughly as "Great Japan," which is how Japan referred to itself before and during WWII. The date appears to be "昭和十九年" or Showa 19, or 1944. That narrows it down to 2 possibilities: the coin is either the 5 Sen tin piece or the 10 Sen tin piece, but we would have to see the other side to determine that. The 10 Sen will have these characters in reverse order: 十銭 The 5 Sen will have these characters in reverse order: 五銭 Before the mid 1950s, Japanese read from right to left and from then to the present it reads left to right. So all of the Japanese typed above also appears on the coin in reverse order. The Sen was also discontinued after WWII. It had the value of 1/100 of a Yen, roughly the functional equivalent of a Cent. Sadly, as already said, either of these coins are pretty valueless even in pristine condition, so the worn and damaged example shown would be worth very little. A decent specimen, one with no wear and a good strike, might fetch $3. Not only that, millions of these were made, so they're the opposite of rare. It's still a fascinating coin regardless. I have a few myself.
That is the 10 Sen. The top of the obverse shows the Chrysanthemum emblem for the Emperor and the bottom has the Pawlonia plant that symbolizes the office of Prime Minister. In 1944, two people who were later convicted as war criminals served as Prime Minister: Hideki Tojo and Kuniaki Koiso. The Emperor was, of course, Hirohito. The coin's date includes his era name, Showa. Those were pretty intense times, to say the least.
These issues have a catalog value of about $1 even in mint state, although tin pest is becoming an increasing problem - these coins were not meant to be collected or stored, and the alloy used decomposes into dust over time. Pristine examples are much more rare than people realize. What fascinates me about your coin is the level of wear. I bought a large lot of WWII era Japanese coins a while ago, and while most of them were bumpy and crumbling, almost none showed any significant wear like yours does. It must have changed hands a lot, because all denominations below 1 yen were demonetized in 1949 with the adoption of Bretton Woods.
