It looks a bit like Honda's CBX125F. This car is a long time old. It seems that some parts have been replaced and are not in their original condition. It is not easy to buy fuel tanks for old cars. You can buy more online. Search this model. If the leaking parts of the fuel tank are not completely rotten, you can go to a car water tank repair shop and ask someone who welds the water tank to see if they can repair the welding. Gluing will not work. If the bottom of the fuel tank has completely started to rot, there is nothing you can do. Welding It doesn't weld well either.
The picture below is Honda’s CBX125