Expert difficulty
Record the top score in Zoo Keeper Tokoton 100 Quest and Time Attack modes to unlock the Expert difficulty setting
Extra hidden difficulty level
Unlockable 4th difficulty gekimuzu
To obtain a 4th difficulty you need to get the highscore on
all 4 modes of gameplay
Zoo keeper 1200000 points needed
Tokoton 100 1800000 points needed
Quest mode 10000 Yen needed
Time attack 600000 points needed
After getting all 4 high scores a 4th difficulty appears in the top line of the option menu
This difficulty means Expert or literally difficultplayer and has a huge advantage of doubling all the normal points you achieve