Was it explained why they don't just use guns? There are gang fights and they have XXI century technology, yet they're still running with katanas. I couldn't reach past 10 chapter, because the fighting with katana is forced. MC enters the gang base and then slaughters over 20 people in a big room with katana. This is retarded. Seems like the author just wanted to create a manga with cool katana fights, but neglected common sense.