[Reutte]

OK, so I have a problem. I'll get back to Japan on March 27th and then head to Kyoto on the 30th. I'm going to stay for about 2-3 days then I need to take a Shinkansen back to Tokyo. However, I do not want to take Nozomi, I want to take the Kodomo or Hikari trains no matter what since they are cheap and I have alot of time to kill. I am also not eligible for a JR pass since I will be in Japan for 4 months. How do I buy a kodomo/hikari shinkansen ticket over the internet? Because I don't feel comfortable waiting till a few days before I leave Kyoto to buy one. I'm really nervous because I don't want to end up stuck in Kyoto with no place to stay since I couldn't get a return train ticket to Tokyo.

Thanks for any help.