All of the reasons above, I think.
Also, this manga doesn't over-sexualize Yuzu, unlike most of the other Loli-Yuri stuff I've seen that contain sexualization of children (like having huge boobs for a pre-adolescent girl, big butt, pee jokes, showing clevage etc.). The author handles the visualization of Mimika's attraction for Yuzu really well, without actually fetishizing her.