Who is this character..?

When Big Mom said 'Now, Then.. It begins! The slaughter show!'
Look at the picture shown by Oda..
Who is this character..?

Is this important..?
Yeah..
We need to identify every characters so that we can predict more on Tea Party that going on..

I thought this belong to one of the Vinsmoke..
Yonji got that robe like the one with gun..
But look at those hand..
It look like it was tied like ribbon..
That could not be Yonji's hand..
Then I realised something afterward..
Reiju said something about Vinsmoke Family was unarmed..
Look at this picture..

So..
I think of Charlotte Dogtooth..
I searched for his outfit..
It also don't match the person above..
Who is this character..?

Maybe someone coming to Tea Party and want to do something there..?
Or Capone asked his men (Vito) to prepare for their assassination plan..?

What do you guys think on this topic..?
Please share your thought with me.. ^^