[BWTraveller]

Skimmed the new chapter, which gives us a bunch more information. The Charm power is indeed temporary, lasting only for a brief period after the target locks eyes with him. It does indeed hit men just as bad as women (poor guy was assaulted by a wall of muscles as confirmation). Additionally, society and the law are naturally very strict when it comes to powers that can be use to control people. For a few more details...

Spoiler:

Kaito is told by the headmistress that his power is going to be forcibly removed. Since this would make it so he can't use magic at all ever again, and he can never fulfill his promise with Mai, he's desperately opposed to this. Somehow his magic power breaks the ties that were holding him and he starts to run, quickly gaining a huge horde of girls and boys chasing him in the throes of his Charm. Mai manages to use magic to knock them all out and then warp him to the room of the seven elites (not sure of the exact translation, but basically equivalent to the Elite Ten in Food Wars). There, he begs them not to steal his power, explains that he didn't intend to use it on anyone at all, it just keeps going uncontrolled. Mai asks him what his goal is, what he wants to do with the power, and says that she wants to become the Highlant, the most powerful sorcerer of all (echoing the promise the two of them made as children to reach that level). He responds in kind that he'll become one of the Seven and reach that level himself. They still say it'd be dangerous to leave him alone, though it may be OK if he had a teacher of some sort. Mai starts to offer to look after him only for Moeka, an older student with a "lust" power, to jump in saying that since her power resembles his own she'd be the most suited to train him, further arguing that it's pretty much par for the course to have some big troubles happen when a person first awakens, implying in the process that there were some big problems when Mai specifically awakened her power. Though Mai seems rather unhappy about it, it concludes with Moeka becoming his guardian and teacher with a one-year time limit to control the power and apply it well.