Looking at term 40 and term 41 seedings, the 41th has more players participating with an extra round on preliminary stage.
On term 40, the prelim was a 4 round single elimination, on term 41 it has 5 rounds.
The players on term 40 who got relegated/demoted (those who lost 3 matches in 5 or less games, 0-3, 1-3 or 2-3) from the c-league, start the term 41 from prelims round 2, thus needing 4 straight wins to get back in c-league.
Also the players who reached the final 4th round on term 40 prelims start the term 41 from prelims round 2. Those on term 40 who lost on round 1,2 or 3, start from prelims round 1.
http://www.nihonkiin.or.jp/match/kisei/040.htmlhttp://www.nihonkiin.or.jp/match/kisei/041.html