He might be richer than the royal... His income came from:
-Royal Treasure (because of him staying there all capital harvest become highest quality)
-Hestia (rent for her room but paid by her service for him)
-Rabbit's Den (The shop rent)
So far we got:
-Exhibitionist Busty Little sister
-Masochist Plot Senpai
-Sadistic Loli Kouhai
-Senpai with smell fetish
-Fujoshi Classmate that into BL
About their achievement, they solves and found the culpirts for those mandrake case, undead case and slime case... 'they' also propose the format for application form... that why the school trust their 'club'
President/Treasurer: Rayforth
Vice-President: Mary
Secretary: Magilca
General Affair Officer: Zack + Safina
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I believe that the right position for each of them