What can I say? I have never before seen a shrine dedicated to Miyagi and Chihaya. It may be that people are afraid to go against the set couple of Kagetsuya and Chihaya (I've only seen one fic where Messiah was included in this couple... err, would be a trio, then). It may be that people can't imagine how Miyagi could be the perfect companion for Chihaya. Miyagi's partner Aya may be so extremely annoying that people looked away during every scene they were in. It may be that Miyagi only appeared for a little while in one OAV and no one even remembers who the heck he is. The world may never know.
Yet, Miyagi reveals so many defining attributes that would compliment Chihaya. For instance, Miyagi tends to expend little energy, and Chihaya is always running around. He can teach Chihaya the wonders of being able to sit in place without moping. It's difficult to even list all the wondrous aspects of Miyagi. He's a calm, but caring man. He's intelligent and doesn't over-react. When Kagetsuya tells him that they truly did see the lucifer seraphim he doesn't treat Chihaya any differently. Rather, he more or less takes the same position as Kagetsuya and keeps the information hidden from Aya. Speaking of Aya, he has the amazing ability to handle annoying anime girls. The way he sits is adorable as it is. When he sighs pitifully at Aya's escapades and rests his cheek in his palm it's even cuter.
I believe that the reason Chihaya and Miyagi had very little time together during the OAV is because the producers of the show realized that if Chihaya had that much time with Miyagi he'd be an idiot to not see that Miyagi was meant for him. Miyagi would easily over-shadow the plot of the show with his incredible bishounen qualities. Kagetsuya would look bland and unnattractive. Everyone would forget they were watching the show for the plot, and Chihaya would seem blind for not falling in love with the man. Had Miyagi received more time he could have easily stolen Chihaya's innocent heart. And who would be better to comfort Miyagi as he constantly faces the wrath of Aya than little Chihaya himself? After dealing with Aya for the entire day, Miyagi would certainly be more than happy to spend some time with someone a little more positive. They're both positive angels anyway, so it wouldn't be hard for them to enjoy the other's presence. Instead of always being with another negative angel they could be together and discuss what they liked about the earthians, and support each other.
There is even a time when Miyagi gives Chihaya a "look". Chihaya is naively holding his little cup of tea and looking in the direction of Aya and Kagetsuya, who are sitting on the couch. While his attention is focused on them Miyagi eyes the young boy from where he's sitting (because Miyagi enjoys sitting, remember?) Chihaya never seems to notice this brief glance. It may also be that Chihaya didn't want to return the favor in front of Kagetsuya. The boy is far too sensitive to share even the subtlest hints of interest in front of the man who cares about him.
One may notice that Miyagi has seems to have developed a strange phobia of standing. It's very likely that this is caused by his partner, Aya. There are only a couple brief scenes where Miyagi is allowed to stand, one is when he is entering carrying Aya's bags and the other is when they are leaving, and he is again carrying Aya's bags. Watch in horror as Aya abuses her beautiful partner, the pacifistic Miyagi. As he stands innocently she shoves him over.