Who knows where is the "hidden button"? I completed all achievements except this on the first run.
If you are looking for tips... well, female classes are crazily overpowered in this game. The most absurd one is the Sorceress followed by Magilancer. Once you have a level 30 sorc with level 7 weapon you can do all hunt quests using her alone, join 3 level 1s in for powerlevel. Even a healer is much more useful compared to a gunslinger.
Needless to say, you can only abuse the apperentice using ranged class. The apperentice appears at random during hunt quests so if you bring a mixed party you may risk unable to kill him (he gives the highest exp). Command wisely using Shift command to teleport your students around, you should be able to block him and shoot safely.
Once you have some low levels and a max healer you can command the healer to not attack, and let these lower level do the job. Exp is gained only for the finishing blow, so avoid attacking with your max healer (keep her under command) unless you absolutely have to or totally understand what you are doing.
5 stars hunt quests is in fact less profitable compared to 4 stars. 4 star wolf hunt is best in terms of exp.
If you start surrounded, run to a clearing and use Shift to gather your students.
Errant quests are actually quite useless. You need three level 30s to complete a 5 star errant at Nice and even so the reward is laughable, except for the money. Eariler you can use this to get more money to buy equipment or more students (even if you gradurate them at level 1 you can get 50 frame but number of students is limited each month). Eventually you will find it quite hard to get 30 of these quest done due to their low appeal.
For tournaments... as said, kill the enemy sorcs first while keeping yours alive should do it. You can use a sorc max and a magilancer max with others level 20+, or just three level 30 with a dummy.
Update: Hidden button is on the credit page. You need to refresh the page, do it and load game to complete this achievement.
Also I found good use of the Duelists, because they have fastest speed and have no use of their mana, you can easily teleport your fellow students around (using Shift to gather students cost mana). Very good in tournament since you can command the duelist, drop on the enemy sorc and call your party in. Also when level 30 he is quite a tank having high evasion.
On my second try I reached year 3 without a single penalty, money per month nearly reached 1200. Though, the expectations of the king is exponential and impossible to fulfill eventually.
If you want a specific class although not too controllable, you can try more levels to see if that student change his or her mind because stat upgrading is random:
Mana Scholar class change requirement: Magilancer: Highest stat in Str Arcane Caster: Highest stat in Agi Sorceress: Highest stat in Int
Apprentice class change requirement: Duelist: Highest stat in Str Gunslinger: Highest stat in Agi Dragoon: Highest stat in Int
Also, note that the advanced classes gives less frame compared to basic class if there are no bonus, so if you just don't have the right classes and need to gradurate some students to make room for new ones, always keep their basic class if their class are not desired at the moment. However, early you will want a high level sorceress for powerlevel (I was wrong, a level 30 sorc can complete any hunt quest all by herself even with the basic weapon).
I recommend doing Errand quests to get enough funds early. You should always take all students available every month. Later, the higher funds per week will allow you not to do any of the Errand quests and take all students, so you can focus on powerlevel in hunt quests.
