Akame ga Kill!, Koutetsujou no Kabaneri Recommendations
Both are anime with very good art, very violent and brutally bloody/gory. In the end, both anime are rather clunky in their execution in spite of how pretty they look and sound. Both could have been significantly better, but if you like good looking high quality action, these are two anime to check out.
For the protagonists, both become a "monster" that is considered dangerous to humans and are (initially, at least) treated poorly by other people. Both have to survive by killing. Lots of blood, lots of gore, lots of death. Eventually, both face a situation where large numbers of people are at risk