another interesting story approach...

We could start our story with a guy (our hero) who just moved to tokyo to be with his japanese fiancee and start a family in japan. HE works some dead end job and the culture is jarring (plenty of lost in translation moments). SHE works during the night as a waitress at a nightclub or kareoke bar... For the first couple months everything is hunky dorky- they visit the sights and sounds, we get introduced to the culture, she gets knocked up...tokyo is foreign but at least he's got the love of his life by his side.

ONE NIGHT, she doesn't show up after work. He stays up and waits for her but the door never opens. As he's getting ready for work, she enters the apartment with a big black eye, she's beaten and bruised but she dismisses it as a simple accident- "some guy at work" OR "i fell down the stairs"

a jealous boyfriend? what the fuck is going on?

Our hero decides to get to the bottom of this, the next day he takes off work and follows her. At first her chores are mundane (a trip to the supermarket, etc). But as the day goes along they get weirder and weirder- a meeting in a sketchy place here, a meeting in a sketchy place there. He soon finds out that she's not a waitress. She's full blown yakuza. Not only is she full blown yakuza, but her father is japan's biggest mob boss....

from here, our hero confronts his fiancee and SOMEHOW gets catapulted into this seedy underground yakuza world...

AT SOME POINT his pregnant fiancee could get kidnaped, which would enable our hero to get in close with this mob boss. This could become a revenge story.