Sunrise Seto Nobi Nobi Seats

Hi,

How do I make the reservation for nobi nobi seats for Sunrise Seto?

On the Jr west reservation website, there are only options for solo, single and twin.

Any advice is welcome!
Very stressed out as I really want to experience the sleeper train.

Thank you!

https://www.reddit.com/r/japan/comments/153pikv/sunrise_seto_nobi_nobi_seats/