Here is a pairing that I completely over-looked the first time I watched the series.
Suprisingly, however, there is a pretty big fan following of this couple (considering how Botan is only in a few episodes) and there were certainly many oppotunities for yaoi proof!

In these pictures, Aya say's he's not interested in "dating" or "playing with" Botan, but Botan says he *is* interested!!  If the writers for the series *didn't* mean to imply a yaoi relationship, they did a bad job, ne?  ^_~

In the following pic, Aya is working away at his laptop in the car (he's the pale hand underneath, of course!) and Botan gently envelopes Aya's hand in his own...  Not to take over control of the computer, mind you.  *Just* for the sake of putting his hand there...
Now *what* kind of man in this day and age, touches another man this way unless he's trying to start something?  ^_~

Twice in the episode, Botan says to Aya directly, "I like you."

At the end of the episode, you see Aya standing alone, watching a romantic sunset and thinking about Botan.  He has even made a paper airplane in Botan's honor.  Aya thinks to himself, "I don't believe in fate, but I *do* believe in you..."  Now, when has Aya said that be believed in *anything*?  I think Botan made a lasting impression...