WARNING! MANGA SPOILERS

I gathered everything known about the Tsukuyomi theory as of ch.60… or everything I know of at least….

Mostly my theories, but a few facts from undergroundsky. I invite you to read through the “Tskuyomi theory” tags for the things I might have missed.

• Introduction: How the theory came to be
  

• Symbolic “coincidences”
  

• Father theory
  

• Spells on gods
  

• Heavens’ involvement

It may have been a hint for Yato’s “Father” role in his survival, but as the chapters releases, it becomes even more likely that it hints at something else. This added with the convenient fact that gods don’t remember their past life spawned an interesting theory:

Yato is not at his first incarnation and he has more than one true name…

He might be Tsukuyomi, the Moon God, brother and supposed fiancé of Amaterasu and many things point into this direction:

(Source of some those facts)

• Moon symbolism: Yato has often came bundled with the moon, especially in important scenes and the link between is even more obvious in ch.37. But first, a little bit of history

Legend has it, that once upon a time, Amaterasu hid in a cave and the sun disappeared from the skies. The celestial body only came back once the other gods tricked her into coming out of her hideout.

A similar event happened with Yato: He was captive in Yomi (a cave) and the moment he was freed, the clouds parted and a shiny full moon appeared. And those eyes……. like two full moons

• Song:Yato’s character song is Tsukiyo no fune (月夜ノ舟) A boat in moonlight. The first two kanji of “tsukiyo” are the same as an alternate reading of Tsukuyomi’s name: 月夜見 (moonlit night gazing?). And 夜 being the first kanji of Yato’s name.

• Water: In some poems, Tsukuyomi was said to have an affinity with water. And the water he possessed could apparently grant eternal youth.  Hiiro was a watery blade for Yato, even Father was surprised by that fact.
  
• Tortoise shell knots: The 卜 in Yato’s name is the same as 亀卜, meaning tortoise shell divination. Tsukuyomi’s role was to oversee those divination sessions… can be interpreted as ‘deciding the fate of humanity’  Yato referenced that form of divination a few times.
• Thread of Fate: “But, you see, Yato-kun… this is something only you can do” -Tenjin to Yato in ch.43 about the wish of an old woman with a pocket-watch chain. Among the other gods, Yato seems to be the only one able to cut down ties, a powerful and potentially dangerous ability to have… and it’s strange that a minor god with no name nor shrine could have that sort of power. Bonds can change lifetimes and influence people’s choices, just like how the bond between Kofuku and poor Yusuke led the latter to suicide. Bonds affect fates… Tsukuyomi was the one overseeing the fates of humans, which might have been the focal point of Father’s interest in taking the Moon God.

Father

He’s a mysterious character, who he is and what he is, is still up in the air. Mortal? God? Half? Part-Ayakashi?

We know that he once went to Yomi and was summoned out by a human who called his name (his beloved?) and those types of summons only work on Gods being called by their true names, so him being a full-on mortal is impossible. Not to forget he’s capable of something akin to divine possession.

Is he Izanagi (Tsukuyomi’s father/creator) or Susanoo, his brother who hated the other gods with a passion and especially his siblings? Both entered the Yomi at one point and successfully left according to legends. And Susanoo was banished to the mortal world, did he lose his immortal body and can now only survive through the ages by stealing other bodies?

Or is Father a mortal who delved into forbidden magic and crossed the line between humanhood and godhood… without being deified. That feat could have landed him under the Heavens’ radar.

But God or human, the hatred he has for gods, with the powers he has, could be a terrible threats to the Heavens.

Powers so great he might be able to curse gods…

Unknown name

I made an observation while re-reading the manga, a strange observation: It’s like Yato is a “shinki-god”. He serves a master and answers to his name (Yaboku) like a shinki would to their master. And that is strangely pointed out by Kazuma when he pretended to cast “Resound” on Yato as spells only work on shinkis.

The purpose of that scene is mysterious. We already knew that spell existed so it wasn’t an introduction to it, perhaps to show Kazuma’s intent of finding who the Sorcerer is? But even then, that scene was superfluous as he pries the information from Yukine not long after.

Unless…

Unless it hints that spells can be cast upon Yato (by his Father). I wouldn’t be surprised that Father is so powerful; I suspect that he even created Nora from scratch or from a spirit (plum-spirit) as her absence of memories rushing through Yato as he named her is suspicious. So Yato might have been put under a spell so powerful it can affect gods. “Name-suppression” is a likely canditate. A spell that was introduced by Kugaha as he suppressed his name “Saku”. Names are everything in Noragami and such a spell shouldn’t be taken lightly.

If that spell had been cast on Yato, being called Tsukuyomi could possibly get no reaction from him.

So yes, being called by the name that would make him happy, truly wouldn’t. It would be a stranger’s name.

But this is only a possibility. Father might have his own ‘deepest secret, like gods hide their shinki mortal name, he hides Yato’s true name without having spells involved.

(EDIT): Father is powerful, we know it, but is a single wish enough to create a god? A single person can a feeble tether to life for some gods, but it’s been implied that a lot of people are needed to create one god. And if Father is that powerful, why should he worry if Yato dies, he could just reincarnate Yaboku to him. Or even better, he could set up his death to start anew, undo the “mistakes”, ie.: Sakura, Hiyori, Yukine. He would have a blank slate to work on again. Why does go through all this trouble? Could it be because he knows Yato wouldn’t reincarnate to him, but to his past lives’ shrine? (Gassan shrine if he is Tsukuyomi)

“But why and how did Father get his hands on the Moon god and why don’t the Heavens look for him or stopped looking for him?”

Heavens’ involvement

Among the higher ups, Amaterasu seems to be only one aware of Yato’s existence and know his true name. Heck, even Kofuku didn’t know he had another name and they’ve known each other for a while.

“I’m…I’m no one worth helping.” -Amaterasu(?)

The Sun Goddess expressed remorse; remorse over what exactly? If the Mighty Goddess feels such emotion to this extent, it must be something truly bad. We knew she came down to deliver information about Yato and only that, so we know what she regrets something about the nameless god, that she feels sorry for his fate. Meaning she did something terrible to him and that ‘terrible thing’ might have been the forced reincarnation and being re-educated away from home or anyone that could have truly cared for him.

Was she the one who sold off her younger brother?

If so, why? In the Nihon-Shoki, Tsukuyomi was branded as evil (a god of calamity) and casted away by Amaterasu who resented him for killing a goddess. But in Noragami, Tsukuyomi might have had a forceful reincarnation after being casted away and what could have caused it?

I suspect Yato reincarnated just after the Age of Gods and Men, just after the Emishi were defeated and then re-educated by the Heavens, because Father lost his beloved around a time period that fit that Age and then got Yaboku not long after.

Is it possible that Tsukuyomi sided with the Emishi? He may not have fought against Amaterasu herself, but more against the corruption thriving in the Heavens: Yato loves and cares for his subordinates/shinki, while the Heavens doesn’t hesitate to use innocent children as tools or even as human bombs to kill off Ebisu.

But no matter what he might have fought against, being caught warranted execution and being a Mighty God, Amaterasu might have had the responsibility of choosing who would re-educate him.

Why Father though? They knew about his powers and his rage against the gods… and maybe that’s why she chose him. His incredible powers might have convinced her that he’d be able to keep Tsukuyomi’s antics at a minimum and that maybe he’d able to change her brother’s nature, to shape him in a way that the “mortal” envisions good gods to be.

No matter what might have been said in their deal, it’s quite obvious that Amaterasu was lied to. Instead of cutting emotional ties and changing the fates of humans, Father recreated him by making him put a blade in everybody and answering to his wishes… culling the herd. Yato enjoys fighting and wielding weapons, but slaughter was something he raised to do by the Sorcerer’s wishes.

“Call him by his true name.” That’ll make him happy. We know she didn’t mean “Yaboku”, as Yato hates that name, but another one, a name he is SUPPOSED to know about.

If Father wants a god to serve him as a shinki would, he would have to hide Tsukuyomi’s name (name-suppression spell as said above). Otherwise Yato could just give him the finger, storm off and return to his big badass shrine on top of a mountain (Gassan shrine)

He’s more useful to Father ignorant and thinking of himself as weak.

Enough about Amaterasu’s deal, what the rest of the Heavens? They don’t seem to know Tsukuyomi (or Yato), they probably never met him (just like Amaterasu seems to be kept hidden) so they’re not involved directly, BUT! they do seem to follow orders about that deal.

Their involvement with Father was hinted back from the moment the Masks were first mentioned. They noticed the panic named Ayakashis were creating and wanted it to die down and as quickly as possible, Ebisu was a perfect scape-goat. Instead of waiting that the god be killed by his risky hobby, they sent an execution force to eliminate him. Kazuma noted that it was over-blown.

(EDIT): Here was a part where the Heavens behaved strangely when they interviewed Yato to enter Kamuhakari and sent Kiun instead of the normal guards. Then I realised Kiun was sent to have a closer look on Yukine as Takemikazuchi doesn’t care about Yato, he remembered Yukine but did not recognize Yato at all. But I’ll add this funny detail said by Kiun about Yato

And who howls at the moon? A wolf XD Or it simply hinted at Yato’s hidden powers

okay back to serious stuff

And then in ch.60, they stopped Bishamon from killing the Sorcerer, the big warning flag. But why do they let the Sorcerer run around though? Why aren’t they bothered by having tougher Ayakashis roaming around. In what way is that good for them? If Father is Susanoo, it might be why they don’t kill him as he is still a Mighty God in someway. But if he is human?…

The tumultous journey of this theory could have its first part confirmed soon: If Nana recognizes Yato, it confirms that Yato reincarnated and did side with the Emishi during the War. And the dream of Yato would only be a step away, being at the top of the Heavens. It won’t be an easy journey, earning back Amaterasu’s trust and his rightful seat as a Mighty God. But Yukine has set him on the right path, it’s only a question of time.