I don't desire either.
It is kinda pathetic that the extra art / title pages keep whoring out the two psychic sisters over and over more often than their actual appearances in the manga proper... Yeah, the female cast is sorely lacking, but in that case just don't bother with the fanservice... as doing it with the same girls over and over again, especially when they have so little plot relevance / screentime, is just really forced.
Besides... as far as partnering / "desire" considerations go, they're both crap. One just looks really fucking ordinary, and the other is an arrogant adult-loli, which is even worse. The only remotely interesting women so far have been monsters... and they were quickly killed.