Poor Mr. Takagi. Director John McTiernan calls him "the one victim of this story." While that's not entirely fair—Ellis may be a butthead, but he didn't deserve to die—it is worth noting that his death is one big, drawn out bummer.
When we meet Mr. Takagi, he seems like a nice man and a good boss. He's Team Holly, he's welcoming to McClane, and he delivers a rousing holiday speech to his corporate troops. This is not a Harry Ellis situation—when Takagi dies, it's not because he's getting what's coming to him. It's because Hans Gruber is ruthless, amoral, and really really wants those bearer bonds.
Most important, Mr. Takagi is a stand-up guy. Against Holly's advice, he reveals himself to Hans Gruber in order to save his employees from further danger. And when Hans questions him, he won't give in. He swears he doesn't know it, and that's a lie. The code is "Akagi," and if we're to believe production designer Jackson DeGovia, that's the name of the ship Takagi served on in World War II (a detail that doesn't mesh with the backstory outlined by Gruber earlier on). Of course, in denying Gruber this information, Takagi is delaying the inevitable by a mere half hour or so, but there's no denying it's pretty noble of him nonetheless.