I've become curious regarding the unusual family name of Rikka noticing that it's written "小鳥遊" but you read it "Takanashi". The reading is absolutely different from what the Kanji are commonly or even rarely read, like there doesn't seem to be any connection.
After a few searches I found out that that family name actually exists and it's not the only one who's that peculiar.
Here in
this page I found an explanation.
Basically "Takanashi" stands for without (nashi) hawk (taka), the kanji say "kotori asobu" (little birds play). Basically the story behind this is that since there is no hawk, the little birds can play freely.
That's a pretty cool family name! Incidentally if Steins;gate taught me well, this is the kind of stuff that is really liked by "chuunibyou", in other words they like to come up with names that have readings completely different from how they are written and are only tied by association of concepts. I'm not completely sure but it might not be a coincidence.
BTW there's another character in this show with an equally peculiar family name: Tsuyuri, written "五月七日" (gogatsu nanoka) which means "May 7". I wonder what's the story behind this one...
Pointless trivia, but I thought that maybe I'm not the only one interested in this.