Artist doesn't tag their characters on pixiv, was buried in another post. This one is much higher res.

I hear that, I lean on saucenao a lot to dig things out of pixiv.

The twitter image is actually the same resolution but twitter's a pain. You'll see images like this:
https://pbs.twimg.com/media/EPiIY6NUwAALad5?format=jpg&name=900x900
You'll want to change the 900x900 on the end to orig
https://pbs.twimg.com/media/EPiIY6NUwAALad5?format=jpg&name=orig

Or if you use danbooru's bookmarklet on the twitter post it should automatically get the biggest image. If you're not using it consider reading up on it, it'll make your life easier.