The only "automatic" qualifier for the coming Olympics is the winner of Nationals.
The second selection must fit at least one of these criteria:
- Second and third placements at the All Japan Championships
- Top two participants at the 2021 Grand Prix Final
- Top three ISU season best scores at the end of the All Japan Championships
The third selection must fit at least one of these criteria:
- A skater who falls under the criteria of the second group but is not selected in that group
- Top three in the ISU World Standings at the end of the All Japan Championships
- Top three ISU Season World Rankings at the end of the All Japan Championships
- Top two season best technical scores in international competitions, the All Japan Championships and domestic competitions as designated by the strengthening department
So for two of the three selections, body of work does exist. Furthermore, there's no specific weighting that is applied; they are free to select someone that satisfies only one condition over someone that satisfies multiple conditions for whatever reason they wish to do so.
It's unlikely that anybody, let alone three people, will surpass Rika Kihira in the ISU World Standings, so even if she shows up at Nationals to just stand on the ice and score a zero for her short program, she can still be considered for the third spot (and they'd be stupid to not consider her in that case).