I ended up biting the bullet and bought volumes 3-5 of the manga.
And man, the last chapter in volume 5 was amazing. It revolves around Nijika and Seika's backstory. If anyone is curious about how the chapter goes, feel free to read the long essay below (the chapter itself takes up 1/3 of the volume).
i almost never comment here, but gosh darn this summary left me a sobbing mess because of how good and real and heartfelt it was. i can't wait to see it in the manga. thank you so very much for providing us with this preview.