@Kayriel
Well, my point is that he has no obligation to do anything for this world. In fact , given how he was forcefully brought there and then given the proverbial kick in the behind because he was not what they wanted, there would be enough of justification for him to be actively antagonistic to everyone around and yet he is gracious enough to only not pull a Voldemort and erase all of those pests with a "erase" command, but to just go travel around in search of good food and books. From his point of view, that war all of those guys are waging around is NOT his problem , it was not caused by him and it is unlikely he could do much to solve it if the parts in question do not want it solved ( and one of them for sure does not ).
Also, Hiiro is definitely not the strongest around ( just to start, the Red loli is surely stronger than him ... and this is not to mention all of the guys fighting around in the last chapters ), so he realistically could not do much against those guys if they actively resist and it was shown already that atleast some of them are all for it and the rest are OK with the situation. If you want powerful people that won't do someting about the war, those guys and gals are the ones the blame, not Hiiro
P.S RL advice: expecting powerful people to do something to destroy the system that made them powerful or that atleast a system they worked their butts off in to get a powerful positon , is ... well, not a inteligent line of action. Also, expecting that anyone to do the things you are unwilling to ( because the powerful ones are suposed to do them ) is quite hypocritical ( not saying you are, just that it is a line of thought that reeks of hypocrisy ).