Very similar to post #1556705 - apart from image size, the main differences I can find are different shading, the open mouth, and this one being sharper. I'd guess that they were colored from the same high-res line art.
I'm guessing the artist has leaked an unfinished bit of this series earlier on Twitter and now we got a full version.
Kokoro love!
Nooo, it's simply that this pic happened AFTER the other one. Kokoro bought the same book (probably from Kourindou) and wants to learn...together. On-hands practice, anyone?