Pretty sure it's waifu2x'd from the twitter version.

1. it's slightly blurred
2. It's 1.4x size (in length) of twitter version

The legit larger version is available on nico: http://seiga.nicovideo.jp/seiga/im5790243

And you can clearly see it's much sharper if you compare them side by side.

I took it from his tumblr.
Replaced with seiga's version then.

Well, it's either Tumblr's algorithm sucks or he uploaded a badly resized version there (Does Tumblr have a max size limit for images?)

Gotta replace it anyway.

But yeah, it's very frustrating when nowadays artists use different social media to publish their work..with various quality. Just stick on pixiv already!

[edit] just tested, Tumblr will resize anything larger to 1920 height.

Aah ok. I see.