User blog comment:Drkness231/Mamono One-Shots! Chapter 6: Lamia/@comment-23603505-20150307044014/@comment-25270168-20150308015200

Explosives can be used in other, non-hostile way, for example to blow up natural obstacles, destroy old/dangerous structures and so forth. Nowadays there are professional pyrotechnicians (I think that's what they're called in English) who are called upon when removing staff in a no-kaboom way is not an option for whatever reason. We can safely assume there are people like that in MGE world, and so our protagonist could be (or not) one of them. He could have "an accident at work", that would also explain him having a bomb for self-defence, as bad idea as it admittedly is. You could also make him suffer from some kind of hearing sense illness, but a bomb accident idea seems legitimate to me.