For everyone questioning why Ami wasn't selected for the WJC the reason is simply because she didn't compete at "Senior" Nationals
which is a requirement to be considered for the WJC team
(IMO, a silly requirement for a Junior Championship but hey, I don't make the rules so

)
She wasn't even listed as a possibility for JW whereas Hana Yoshida and Rino Matsuike were
The only issue I have with this decision is if you consider the allowed quota for Junior skaters at "Senior" Nationals, Ami
could have received an invitation to compete regardless of her finishing in 10th at Junior Nationals
Not sure why, but ultimately, the federation decided not to invite her (my positive take: they didn't want to encourage her or others to compete while injured...?)
According to the guidelines, exceptions to the "must compete at "Senior" Nationals" rule can be made in unavoidable circumstances such as injury for skaters who placed within Top 3 at the previous WJC...which Ami did
I can't be certain, but my guess is if she had withdrawn from Junior Nationals citing injury, though this decision would've disqualified her from participating at "Senior" Nationals, she might've still been considered for the WJC team due to this exception