You cant buy it if you're not in Japan, i tried visa and master card not working. anothe methonds only if you in Japan. Sadly.
If you are in fantia.
You can select Charge COINs (Purchase at Tokyo Otaku Mode) when subscribing, and then choose to purchase at Tokyo Otaku Modeでチャージ. ヾ(•ω•`)o
It should support the use of paypal or visa, etc.
