James Cagney and Margaret Wycherly in White Heat. Below, their Japanese counterparts.
Nice work, mom! Instead of a shiftless yakuza, your boy is a reckless misfit who robs from the yakuza. While other characters affect the same retro fashions Bunta likes (we're probably seeing a Godfather influence) his preference for an anachronistic costume and a distinctive weapon (we're told that he's a prime suspect in the drugnabbing because not many Japanese use machine guns) suggests an arrested development, stunted by his suffocating mother. It's left him a big, crazy kid who spends his life role-playing with lethal consequences for others, as when he stages a St. Valentine's massacre of gangsters who tried to blackmail him.
Fernando di Leo's Manhunt) send a distress call to America and get a black-and-white team of hitman to hunt down Bunta and his ragtag gang. The yaks run down Bunta's biker pals with garbage trucks, while the Americans take to throwing them off tall buildings, but none of these losers know where the drugs are stashed. There's nothing to do but storm Bunta's hideout, but he sees them coming, sees he's outnumbered, and quickly thinks up a way out. He has his new girlfriend slash her own hand and call the cops. Bunta saves his neck by getting himself arrested for domestic battery right in front of his enemies.
Americans have no manners. Look at the mess they leave behind when they go out.
In the original, Raoul Walsh sets us up by having Cagney pass a request for info on his mom across a row of cons in a prison dining hall. We see the query relayed one way, and the answer sent back the other way until the news hits Cagney, who takes a moment to absorb it before (as a full-of-it George C. Scott says from the grave on TCM) he becomes an animal and runs amok.
The do-over in Machine Gun Dragon is less elaborate but arguably more devastating in the set-up. It's visiting hour for our protagonist, who rushes from cell to visiting chamber anticipating Mom. Instead, it's his girlfriend with some sort of package under her jacket. Bunta immediately realizes something's wrong. He's having a "what's in the box?" moment already before the girlfriend unveils the package: a box of Mom's ashes.
Edmond O'Brien (right) and his Machine Gun Dragon analogue (below)
We can tell, however, that Bunta isn't the hardcase he pretends to be. He took his mom's death too hard for that to be true. He faces one more test when his pursuers capture his new girlfriend. He's got his boat and his drugs, but they have a straight razor to the girl's throat. They propose an exchange: her for the drugs. In an appalling moment, he tells them they can have her and leave him alone. You can almost believe that he didn't expect them to do what they do.