You guys are still on this, huh...? From chapter 1 to chapter 6 has all been in the span of the same summer. I'm like 99% sure of this. Takeru shows up in chapter 3 and that's when you learn that he likes Sou, and then in this chapter you see Nozomu remembering that night, which Takeru is still upset about. The seemingly random colors are anyone's guess at this point. It's only been 2 chapters so there's no way to figure out the rhyme or reason.
I meant more that this happened some time ago, and he's looking back with nostalgic glasses or something. Though the guy has a smart phone and the tv is a flat style tv, though it still could be from like a decade ago.
The color tones feel similar to the usual magazine raws (if you had physical and not digital), so I think that it's to mimic reading old magazines. I can't be sure though, but I do think there's a meaning behind the tones besides just making people buy the volumes instead of reading on comicwalker.
The tawawa guy has a gimmick of having blue tones for his work, but he's had for as long as I can remember even before he started with tawawa.