The story sets in America, and revolves around two characters named Ein, a well named assassin who’s feared as the mighty “Phantom” and Zwei, a Japanese high-schooler who was brainwashed and forced to join an underground organization, as they try to survive, living a life forced upon them by a man named “Scythe Master” under an underworld organization called “Inferno”. As the Anime progresses, you’ll get to know their lives through the eyes of a brain washed person, while having an internal struggle to fit in the world he was forced to live. But that might change over time.

#(+) points

• The Setting: For an Anime following an assassin, it does a very good job to capture that environment. Mysterious hideouts, a massive building for an underground organization, the shopping Mall from the eyes of an assassin and etc.
• The Main Characters : The characters aren't exceptionally great or well written, but they are written good enough to keep you entertained. "Zwei" and "Ein", two memory whipped people, who are feared as the "Phantom" in the underworld, have an interesting chemistry between them.
• The Music : The creepy opening theme, the slow burn sad music during the first half or the badass SuperStar soundtrack during the second half, the music doesn't let down and elevates the scene or moment it's being used.

#(-) points

• Time Skips & Tone Shifts : The Anime can be divided into two parts. The first half focusses on the main characters, while the later half is where the world building happens. What started as a insightful look on assassins changes into an political crime drama between gangs. While it isn't bad, the mood and tone of the shows changes which can/might disappoint a few people.
• Plot holes in later half : I started to think at a certain point in later half if the writer had changed cause some things doesn't make sense and feels illogical. After time skips, some characters doesn't even seemed aged well, while a certain cute little girl changed into a busty woman in only 2 years, which makes no sense considering the remaining cast. While you might be thinking, "It's Anime so logic doesn't apply", this Anime wants audience to know that the setting is very similar to real life. It reflects even in the characters, from design to dialogue, they don't feel like the usual Anime fluff but as mature characters from a mature show. It really breaks the immersion the Anime built up so far, which makes it very unnecessary.
• The Ending : See, this is the case which proves that the ending can make/break an Anime or show. Even if the show had a great beginning and middle, if it doesn't land the ending, it can make it a very mediocre one. That's exactly case here. The Ending tries to make you feel something, but it comes of the otherway, i.e, mediocre. What should've been good closure after everything the characters went through, ends up like a train wreck, that makes you feel everything is just.... pointless. I just couldn't care about it anymore.