Devil Summoner: Raidou Kuzunoha vs. the Soulless Army/WMG
Raidou is bald.
He's a man with spiritual training. Depending on the extent of the Buddhist influences on the Kuzunoha clan's traditions, he may be required to keep a tonsure. But he's vain, so he only does the top and wears a hat to cover it at all times.
Raidou's hat is the true source of his power.
That's why he can never take it off. Narumi's hat is the source of his detective abilities, too. In fact, the entire game runs on the power of Nice Hats.
- But Satake is quite powerful (enough to take out a Super Soldier with his bare hands, more than Raidou can say!), and he doesn't have a Nice Hat...
- Well, clearly he's just that badass. We don't know how much more powerful he could be if he did have a Nice Hat.
The Shin Megami Tensei main series (and Imagine) and the Persona series (and possibly if...) are both possible/alternate futures of the world of DSRK
Clearly the canonical future is that of the Shin Megami Tensei main series, since that's the one we see in the Akarana Corridor and the one the crazy Messian Raidou possessing Kaya came from. However, Persona 2 also features Kuzunoha summoners, who seem to be running a detective agency -- which would make sense if Raidou got a taste for detective work during his time with Narumi and decided to set up his own business later on. It could just be meant as a Mythology Gag / shout-out to the earlier two Devil Summoner games, but there's no real reason why it couldn't be the future of DSRK... except that the main series timeline and the Persona series timeline are completely incompatible. But we know that alternate universes exist, and that history doesn't always take the same course in each of them, so...
- We think alike. Just look at what "Raido" says when he encounters our hero. "I sense a strange presence, and before me stands my shadow." Then, if you state your name: "They must be our shadows, why would he give my name?" This reference to a doppelganger called a shadow that is most certainly your shadow if it calls itself the same as you... it sounds familiar. This plays into the forefront of Persona 4, and is briefly touched upon in Persona 3. I don't know about the other games in the timeline, but I'll look at the alternate space/time again when I get there and see if I can't dig up any more clues.