Why is the anime's opening theme is titled 'Family'? Because Family is one of the major themes in the anime.
The anime's ending is tragic, or rather, bittersweet, but why the melancholy tune that plays during the last scene is titled 'Happy Ending'? Because before dying, the Tragic Heroes who have been enemies are friends again. It also rings true with Mika's words at the end: "Welcome home."
Looking through Brandon's point-of-view, it can be said that his job is done. Mika is no longer targeted by Millennion and he's friends again with Harry, who earlier turns from his best friend into his mortal enemy. Also, as stated by Dr. T, Necrolyze is a cursed technology and is also why Big Daddy is angered when finding out about Brandon being Necrolyzed. Brandon himself is a Necrolyze, but when he dies, he's no longer living as an undead (see the Fridge Horror section about Brandon's color scheme in the last few episodes); he's at peace. Due to Brandon's lack of self-interest, this may be the least he cares about unlike the aforementioned issue with Mika and Harry, but still.
In the first few episodes (except episode 1, which is due to the In Medias Res nature of the anime), Brandon is portrayed as a Technical Pacifist who Does Not Like Guns. But why does he become a hitman? Because of his Undying Loyalty. If being a killer is what he can do to help Harry rise to the top of Millennion, he'll just roll with it.
It's easy to tell that Kenny's gun is a toy gun before the revelation. Kenny hesitates to draw his gun when he is faced with Deed, who has a gun (although it's also a fake).
Scott, the treacherous Knowledge Broker before Brandon and Harry join Millennion, is the same person who gives Mika information in episode 19. There's a hint that he actually never dies. In episode 6, when Brandon has a nightmare, Scott's body is not seen among flashes of the corpses that Brandon sees in the past.
The battle between Brandon/Grave and Bunji in episode 24. Why doesn't Grave use Anti-Superior bullets immediately? The title is 'Last Bullet', and Grave is probably short on Anti-Superior bullets supply and saves it for the best chance. In the next episode, he has no more bullets by the time he meets Harry.
This leads to another one: Brandon pointing his gun at Harry probably means that he actually wants to shoot Harry, but he just can't.
Where do Grave's cowboy outfit and coffin go? Clothing Damage happens in episode 22, while Bear's katana destroys the coffin in episode 23.
Harry saying "Another form of human nature" in episode 23 when he sees Bear's farewell to Sherry. It hints that Bear has undergone Superiorization.
'Mad Dog' Ladd's relationship with the mafia and why Bear attacks him. At first, it's strange to see why he attacks a lab and spares Dr. Tokioka, who then follows him. Much later, Dr. Tokioka is seen working with Lightning, Millennion's enemy. Ladd is actually on Lightning's side all this long.
Why does Ladd attack a lab and recruit Dr. Tokioka? After the five year timeskip, Cannon Vulcan says that he has been developing Necrolyzation technology for seven years. It's possible that after two years of research, Lightning needs more scientists for the development of the aforementioned technology.
It's a blink-and-you-miss-it. During the finale, Harry still has his wedding ring on his finger. This makes Harry's reaction to Sherry's death even sadder.
Since the end of episode 14(the episode in which Harry murders Brandon), the ending credits start rolling in black and white, symbolizing the dead friendship between Brandon and Harry. But when the two meet face-to-face again in episode 25, the ending credits start rolling in color again. Guess whathappens in the next episode.
Brandon's/Grave's wish near the end of the final episode before attempting to do Mutual Kill with Harry? "Let's go back." The credits that showcase the characters calling Brandon's and Harry's names are mostly played in reverse order, depending on who Brandon knows first (except Sherry, who is first, presumably because Brandon doesn't really know her). After the credits, it ends with the flashback of how Brandon and Harry first become friends.
Brandon's Workout Fanservice in the second episode looks like just something mundane, but it actually highlights the scars that Brandon has as Grave.
The universe's definition of family as stated by Gary and Widge: it's about not betraying each other. Meanwhile, Big Daddy's Millennion enforces the Code of Iron, which is executing traitors to ensure loyalty to the organization. In other words, the term 'Family' fits Big Daddy's Millennion to a T.
This definition makes the anime's OP theme more meaningful.
See also the Fridge Horror section regarding Mika's speech in the finale.
The Cerberus in the anime. Brandon only uses them to dispatch undead like orgmen, superiors, etc, but he never shoots humans with them, not even Harry. And he does that to protect Mika. In Greek mythology, Cerberus' task as the guardian of the gate to the Underworld is to keep the dead from escaping the Underworld and prevent the living from entering the Underworld.
In episode 15, Bunji leads Brandon's True Grave (because Brandon is dead) and renames it as 'The Kugashira Group', but it's never heard again. Then in episode 19, Scott says that Bunji is a lone wolf and anyone who works under him always ends up dead.
Because Millennion is soon known to use people's corpses to create Orgmen, is it possible that the squad ends up as Orgmen?
And then Brandon/Grave destroys those Orgmen?
Brandon lives by the code of 'never betray', but by the time the anime ends, one may find that Brandon actually betrays Millennion. If he's loyal to the syndicate, he's supposed to enforce the Code of Iron and execute Harry when Harry reveals his plan of betrayal. But he doesn't.
However, by the end, Brandon actually betrays both Harry and Millennion. albeit partially (and perhaps, inadvertently). He lets Harry slip, attacks Harry's Millennion to protect Mika, and lastly, injures some agents from the new Millennion to protect Harry.
Alzac Tino is chosen as Big Daddy's successor in episode 14. Later, Harry says that Alzac suddenly falls ill. In the last episode, while Brandon and Harry talk and argue, Alzac's ghost is standing in witness just like all the deceased characters. And then there's Harry talking about Alzac too. What has Harry done?
Crosses over with Fridge Brilliance: In the last three episodes, Brandon's color scheme starts to change. By the time we get to the final episode, his hair is paper-white and his skin is a brownish-grey color. At first, this seems like a rather mundane detail, until you combine it with the fact that his movements are getting stiff. Remember what Tokioka said about Grave going back to being dead if he doesn't refresh his blood supply? By the final episode, his movements are stiffening thanks to rigor mortis, his hair has slowly lost its pigmentation, and his skin is essentially drying out. In other words, he's decaying. While he's still awake.
This gives a whole new meaning to Harry's quote at the beginning of the final episode:
Harry: You look like a dead person.
There's a moment when Bear asks about having grandchildren. Then Harry says that he and Sherry are still attempting. In the flashback, when Harry and Sherry get married, Harry's appearance is similar to how he looks like during episode 12 to 16 (around thirty). It means that after over ten years of wedding, they haven't had children yet. Infertility?
Gary and Widge have explained to Mika that family is a bond that exists between people as long as they don't betray each other. Then, Mika and Brandon/Grave agree that they are a family, meaning that they won't betray each other. In the end? A variant of Bodyguard Betrayal ensues. Brandon chooses Harry over Millennion (Mika). And then, Mika still considers Brandon as her family... Harry is the one who murders Mika's parents, yet Brandon protects Harry and ends up seriously injured for him in the end.
This leads to a Fridge Logic. Why the theme that plays when Mika gives that speech is titled Happy Ending? Dude, Not Funny! However, the ambiguity of the ending does allow the subversion of this Fridge Logic.
The graves of Maria and Butler Tokioka. Are they empty graves or how can they retrieve their bodies?
Bunji is almost always seen smoking, even in the second game, where he's a deadman. Regarding that second bit, how is he able to smoke if he's undead, given that his lungs shouldn't be working anymore?
Combined with Genius Bonus. Anti-Necrolyze bullets cause necrosis, which means tissue death. Then Bunji says that it's especially effective against dead tissue. Deader than Dead?
