Here is the selection criteria for Japan Chess Championship from 2020.
1. The winner of following Championship Tournaments from the previous year:
– Japan Chess Championship, Japan Rapid Chess Championship, University Chess Championship, Japan Youth Chess Championship (U18, U16, U14 categories)
*Also top female player from Japan Chess Championship
2. Top 2 players from Japan Women’s Championship and Japan Senior Chess Championship from the previous year
For 1 and 2, if the winner does not hold Japanese FIDE ID, the top Japanese FIDE ID holder will also qualify from the tournament.
3. Top 5 players and a top female player from Japan Chess Classic and Japan Open from the previous year
4. Top 20 players listed on NCS February Rating list
(Active players* only, excluding players who qualify from 1,2,3)
5. One player for every 8 participants at all qualifying tournaments, plus 1 player from the hosting club**
(<8=1player, 8<16=2players, 16<24=3players…and so on)
*Active Player – Players who have had their NCS rating calculated at least 3 times between June and December. Players who have had their FIDE rating calculated more than 3 times in the last calendar year.
**Each hosting club organizer decides on the term of a club qualifier
Above rules only apply to NCS yearly members. 1-time tournament members do not qualify in any tournaments.