It's in the middle of nowhere (Osen) makes it easy to make people disappear
Mc and rin both already knew something was off and felt it might be them coming.
if and i mean if Mc and rin both dont think it might be them, Then they are both stupid and are going to be killed faster and easier,.
one of those not being aware of your enemy. and since they are both aware they know it was them. since tomoko was scared and hurried them out.. Mc even says that japanese people would stand out in there area since its more Korean or Chinese based. so they def knew.
That is what Rin and Ryker known. That isn't what Eito know or the Assasin (or even Hanako). It also isn't show if the cam including audio or not. Assuming Eito it wouldn't suprise me that he was too stingy to pay the extra for it.
4) that point has merit but i don't life in the US but i wouldn't get Information on a small scale murder that happened in another state or even a city a few hours away if the culprit didn't made a spectacle out of it. So im sceptical that a murder in the woods hours away would reach Rin in Berdoo, MC would probably hear about it if he digs into it but he thinks its the Yakuza to beginn with.
What is the benefit for Yakuza?
They kill Eito and Hanako and gain almost nothing?
Can Eito pay them back as it is? Probably not.
Will Ryker and Rin (or whoever go at the second time) be suprised that some Eito and Hanako are nowhere to be found and some other are there? Or that the Onsen is closed?
So, the Yakuza send one agend to Onsen immediately after they hear that Rin was there. Thus, I assume she is a high priority for them and also that they don't have any other leads (worth checking).
Futhermore - I've peered into Dima's notes:
They will setup an associate or agent at the Onsen. Perhaps her, I would assume another not that the one we already seen. They will inquire about the poor arse car with it's licence plate and probably for our lucky bastard, this lead will let them go to the wrong state. They will inquire about Ryker what, most likely, will lead them to the hotel and Fox Box after some time.
And they will take compensation from Eito or Hanoko, which will means that Eito will lose money
or body parts - Dima's note say
pinky - and Hanoko might be enforce to do more lend act to cover for Eito's debt.