JR 규슈 후쿠오카 와이드 모바일 패스
The JR Kyushu Mobile Pass is a ticket that can be used on your smartphone without needing to exchange it at the station window. You can access it anytime from your phone and don't have to worry about losing or damaging it, allowing you to travel freely in Kyushu with ease.
https://www.jrkyushu.co.jp/english/railpass/mobilepass.html
*It is not possible to purchase individual tickets for children.