Isekai de Maou wo Taoshite Nihon ni Kaettekitara, Chijou ni Dungeon ga Shutsugenshimashita Chapter -- Discussion

the MC wants to keep living a quiet life and has to protect his sister from danger but even though he has the means, he didn't think of taking the most obvious actions for it, like wearing a mask to hide your face or using your transparency magic from the beginning when doing something flashy.

Result: he keeps getting entangled in people's selfish desires, a bit frustrating