Some things are because of that simplified but still close to reality as much as possible.
This database is something I did just for fun, my main database is from Czech Republic that has more than 450k changes and has 8.divisions and whole junior system so if you want to give it a try link is here:
https://www.fmscout.com/a-czech-lower-leagues-fm22.html
This database doesn't include players or staff but if you use them from other database it is fully compatible.
Database includes
J1 LeagueJ2 League
J3 League
JFL
Regional Leagues Division 1
Regional Leagues Division 2
Emperor's Cup
J.League YBC Levain Cup
Fujifilm Super Cup
Prefecture qualifications round for Emperor's Cup
All-Japan Shakaijin
Prime Minister Cup (University Cup)
Youth Pyramid:
J-Elite (U21 competition for teams in J1)
Japanese Under 18s Premier League
Japanese Under 18s Prince League
Japanese League Club Youth Championship (for U18 teams from teams J1,J2,J3)
Japanese National High School Soccer Tournament
Japanese National Inter High School Championship
Because rules of promotion and relegation between J3 and JFL are very complicated, it's simplified and first from JFL and last from J3 plays one match play-off
Play-off between J1 and J2 is like in real life.
Promotion from regional league to JFL is little simplified, all 9 teams are divided into two groups where 2 best go to next round where 4 teams play once with each other. First 2 than play play-off match with 2 worst teams from JFL. (the difference is that in real life there can be up to 12 teams in this play-off)
Configured are prize money, TV money, registration of players, number of foreign players in match
I simulated 6 seasons and everything is working how it should
Discussion: Japan Lower Leagues (D6) for FM22 by Tenshi
2 comments have been posted so far.
You are not telling me lots of informations here too, do you use any other db? do you start in year 2021 or 2022? Because db is made to start in 2022.
I increased reputation for Mitsubishi Mizushima and simulated two seasons, everything is working fine which you can see on screenshots here:
Season 2022
https://i.imgur.com/1xoLI9J.jpg
https://i.imgur.com/KjP9dqx.jpg
https://i.imgur.com/uhrMoCy.jpg
Season 2023
https://i.imgur.com/6c5wryK.jpg
https://i.imgur.com/P6bHOQy.jpg
https://i.imgur.com/dOJPQxn.jpg
So yeah, everything is working, the fault is on your side.