I read a foreign manga and in it there's a circumstance where a boss gave one of his subordinates a job/task, and said something like "You are in charge of it now."or"It's your job now." Is there any more colloquial way to express the same meaning in English?What sentence do people usually use when they hand over a job to someone?
You can use an idiom like "pass the baton" or "take the wheel" or "manage the helm" etc.
As the present great leader of this company, I now pass the baton over to you.
I used to be the boss here, but now I'm asking you to take the wheel.
You're managing the helm now, get to work and keep me apprised!
that's your, his, etc. problem / that's (someone's) problem TFD idiom
That is something someone else will have to deal with or figure out; that's not my responsibility or concern.
What sentence can people use when they hand over a job to someone?
If the job has been a problem, or one has received undue criticism for its management:
That is your problem now!
it’s/they’re ˌall ˈyours another idiom used when passing the responsibility for somebody/something or the use of something to another person:
The job is all yours ... now!
To take control of something, especially an organization or a country, is often known as taking over the reins
Source: Cambridge Dictionary
To 'run point' is one expression for being in charge, though it might also imply to have command over other people of a similar 'rank'. A superior might say:
"You (are) run(ning) point on this."
take over comes to mind
to assume control or possession of or responsibility for
(Marriam-Webster) as in
You take over.
It’s your baby now!
…is as colloquial as it comes.
As for external support for this, Googling just gives information about bringing up children. However if you think about it, the literal use in the lyrics from eponymous Elvis Presley song hint at the colloquial meaning.
It’s your baby, you rock it It’s your heartache, you bought it You made the bed you’re sleeping in And I’m tired of hearing about it friend