[Nankai Airport Express tickets valid for day of purchase only?]

On 9/7/2019 at 8:37 PM, Japan Station said:

There are two types of Nankai Airport Express trains:

1. The Airport Express commuter train. No reservations are required for this train and the journey time is about 44 minutes. Boarding time is not specified on tickets. IC cards like ICOCA can also be used.

2. The Rapi:t limited express service between Kansai Airport Station and Namba Station. All seats on this train are reserved. Tickets are issued with a boarding time and seat number.

You can find more information about Nankai Airport Express trains here: https://www.osakastation.com/the-nankai-airport-line-the-airport-express-rapit-services-for-kansai-airport-namba/

 

Where can i buy tickets of rapi:t limited express?