Unfortunately, I haven't seen "Tonde Buurin" yet, so I can't 
write this one, but it would be kind of neat for Karin what's-her-name to 
get a schoolgirl crush on Ryouga and him seeing her as sort of a little 
sister while neither of them suspects the other's alternate identity. 

SKJAM!
(Or maybe even a possible full romance, if the fanfic author doesn't like 
Akari :0)