It's a anime version of John Wick. I loved everything about it. From the plot, characters, their developments, interactions, sequence, tension and the ending. One of the most underrated series that could even be on par with animes like Code Geass. It even has some lighthearted moments during the second half of the series. This anime allows you to see different types of people. For example good people who made bad decisions or a horrible manipulator who in fairness isn't called a master for nothing and more. It was very realistic from start to finish so even though most people didn't entirely like the ending especially, I did.