@YuriSenpai the origin of Nontanu and Kitsunechika is from School Idol Festival if I'm not mistaken. They get animal costumes and as you can see Eli is a fox and Nozomi is a tanuki.
The shyness feeling seems to be mutual, even if Kuro's significantly more outgoing. Perhaps it has something to do with the taboo nature of their incestuous relationship (see the tags)
Nico and Hanayo would make a great pair. They'd go on idol concert/event dates together and just fangirl over cute idols. Then in the end, they end up fangirling over each other.