Would like to know that why Highway Bus online reservation not available from Shinjuku to Kawaguc...

Hi.

You can make an online reservation from Shinjuku to Kawaguchiko for up to 5 people at once from the link below.
http://highway-buses.jp/

However, if there are not enough seats for the time slot, you may not be able to book for 2 people.
Please try choosing a different date or time.

Also, please note that you can book your ticket only from one month ahead of your departure date.

Thank you!

Japan Trip Search

Hi there,

https://www.highwaybus.com/gp/foreign/frgSelectBordingDate

Please try again the link above.
It seems it's working now..

Hope this could be your help