Typically when an anime airs, it's resolution is 1280x720 and gets downscaled to 853x480, 640x360, or even upscaled to 1920x1080. However, one of the odd things I noticed about Grisaia no Rakuen is that it has black bars on the top and bottom; removing these black bars shows it's true resolution: 1280x544, which is particularly odd. Is there a reason why they drew/animated/produced Grisaia series at a weird resolution?
According to a Gigazine article that reported on a 2 May 2015 panel at Machi Asobi featuring some of the Grisaia staff, it seems that Tensho (the director) just really wanted to do an anime fully in a cinematic aspect ratio (2.35:1 / 21:9 / Cinemascope) and refused to compromise on this point. Tensho does not appear to have elaborated on his motivations, at least not at this particular panel. So, chalk it up to directorial whim, I guess?
Incidentally, according to a tweet by Tensho, Grisaia no Kajitsu was in fact the first television anime to be produced entirely in Cinemascope. Apparently, they had to place a special order for paper with that aspect ratio since they wanted to draw on paper that was genuinely the right size (rather than just taping over the top and bottom of standard 16:9 paper).
I should add: according to Anibin, Grisaia no Kajitsu was actually produced at a native width of 1920 pixels (equivalent to 1080p video), so its "true" resolution is roughly 1920x822, not 1280x544. This is still something of a rarity (I think with the exception of Kyoto Animation?), though we're seeing more shows pop up in full 1080p nowadays, e.g. Working!!!, airing now (in summer 2015).