is my 5 years 4 months old kids free of charge ?

hi, im fredy from indonesia.
i will visit japan for vacation with my family on 7-15 April 2024. i will go with 4 adults and 2 kids, my kids. My kids are 9 years old and 5 years 4 months old ( born at 20th Dec 2018 ) on April. So my question is , that my 5 years 4 months old kids is free of charge, or must pay for a half of the price ? because i see on JR web, kids 6-11 years old have half of the price, and below 5 years old is free of charge..
thanx for your answer