Not really evidence ...

Ok so, I'll try to collect some Ryuki stuff that is considered as evidence but it's really not, even though that'll be hard since there are only a few Ryuki pages left ... :(

They look cute together. -> Ok, they do but so do Kazu and Kenta and they're not (necessarily xD) gay.

They both wear a kerchief around their necks. ->I remember this one! I read it on one of the Ryuki pages that doesn't exist anymore a few years ago. xD I think it's a good observation but still ... this is probably just coincidence! Or is it not? :o

Their D-Power is blue. -> Not quite the same but they both have a blue D-Power (Ryo's is just more blue than white and Rika's more white than blue (and blue is lighter)). This really is an interesting one! I googled the meaning of blue colour, if it has something to do with Rika and Ryo. See it here!

Purple & Blue -> Have you ever realised that Rika's eyes are purple and Ryo's blue? There's no connection if you put it like this but if you think about the colour the two have when they digivolve to mega level, there's an interesting connection! Ryo's colour is purple and Rika's blue. Ryo's mega level colour = Rika's eyes; Rika's mega level colour = Ryo's eyes! ;D (Yeah, that's way the new layout is called Purple & Blue xD)