Strange Japanese text pop-up

Hey everyone, I've been having this strange notification pop-up the last few days, and I can't figure out what's causing it.

It seems to happen randomly, and it's in Japanese so I can't understand it.

Running a Nexus 6, stock firmware and ROM, not rooted.

Here's a pic: http://imgur.com/pS9H0oZ

Got this weird japanese toast messages. how can I trace which app is generating them?

Hi there. I keep getting any now and then some toast messages in japanese which seems to send some packets from my phone. here they are

I'd show you the screens but the forum prevents me to post images right now

I've got a Moto G 3rd Gen, running latest android 6.0
I listed all the apps running in my phone but none seemed suspect, just usual stuff from the play store.
can you help me identify is this is a malware sending some data from my phone? I totally have no clue

Japanese HTC model keyboard

To owners of the Japanese HTC 10, what keyboard is installed to input Japanese?
With US models, TouchPal is installed and that does not have a Japanese option.