The company behind the TVpad now has an English webpage, making it easier to buy the product:
TVpad English order website (TVpad2 and TVpad M121S English order page)
The discount code 14696673 is still valid on the English website and it can be used unlimited times.
Also, a new app is now being tested, which has 25 Japanese TV channels. I will post the new app when it's officially released to the public.
