Summary
Magnus a mage who always got yelled at just shut up and follow my orders by the Hero because he was deemed useless One day after getting feed up with his party he left upon leaving he met a merchant that sold him a mysterious book
And it turned out that the book which was written in the gods language was actually an ultimate encyclopaedia book that had a lot of useful information on how to defeat the Demon Lord
Thanks to that book he was able to know about boss monsters weaknesses and raise his level more efficiently data about important people and it even had info on complete gourmet spots in any city Moreover by using his wits and scheming mind hes even able to outclass the hero party With the ultimate encyclopaedia in his hands advance to the true route to defeat the Demon Lord
Magnus wasnt chosen by destiny to be the hero Thats why Hes going to beat the Demon Lord with his own power and wits and save the world