i dun think its the grandpa tho. since one of the guarding dragons described in seeing someone with his features too that he absolutely sure it was not reiko (one chapter) . but not sure grandpa or his father tho. but i have a feeling the grandpa was able to see youkais too so i suspect is the grandpa

More questions than answers though... although I'm happy to see there are dragons spirits included too in NY :D

Hello, I come from the future and already encouraged the dragons talking about the "grandfather".

By FireCrauter . (M.a)

Sponsored by: Google translator

I need theories :(  I don't know how else I'll survive until more chapters are published

There was a episode that takashi got a cold but then the middle class youkai got him a medicine to cure his cold and it did cure takashi however hinoe said that the medicine only works for youkai. A lot of people speculate that takashi is half-youkai and that his grandfather was youkai however this theory was abolished since hakozaki's dragons said that they met someone with a similar features like takashi and that it was a man. In this chapter, it was hinted that takashi's grandfather was an exorcist. In chapter 80 mr. yorishima was introduced and that his clan used to rival the power of the matoba however their clan has pulled out of exorcist buisness. Natori said that mr. yorishima was pretty old and that there were rumors  that he is a half-youkai and that his left arm was devoured and that an ayakashi turned into his left arm. Maybe that their clan has the power to do those kind of shits and that takashi's grandfater came from this clan because 1. he is hinted to be an exorcist 2. that he maybe he  has youkai inside his body like mr.yorishima and it was pass to takashi explaining the why the medicine worked on him when it was only meant for  youkai. Maybe mr yorishima is takashi's grandfather after natori stating that he is "pretty old". so yeah that's pretty much my theory

Maybe the man that dragon mentioned wasnt takashi,s grand father maybe he was his great grand father or something a And takashi might be a half youkai or something And i think madara might be his grand father And the nice man reiko mentioned might be madara in human form and as you can see sometimes takashi or exorcists cant recognize youkais from humans so its a possibility that reiko didnt know the man he liked was a youkai Maybe thats why at somepoint she started hating youkais too because of findig out that she was being deceived by some man she loves which actually is a youkai who is pretending to be a human which leaves her heartbroken and she might have sealed him in that shrine for revenge or some yhinh ( sorry about bad english)

My theory is that nyanko-sensei knew Natsume's grandfather. His grandfather may be an exorcist and met Reiko, Natsume's grandmother, who can also see youkai. Maybe he taught Reiko some knowledge about spells and talisman. I've read a post before that Natsume's grandfather was the one who introduced nanatsujiya manju's snack. Maybe nyanko-sensei is Natsume's grandfather's familiars? That's why nyanko-sensei also wanted to be close to Natsume their grandson to protect him?

I really like the "Nyanko-sensei was Natsume's grandfather's familiar" theory. It honestly makes a lot of sense. I had some thoughts initially about Nyanko-sensei being somehow blood-related to Natsume because of how unusually attached he is (any other youkai would have killed Natsume and taken the Book of Friends) and because of the fact that apparently he knew Reiko fairly intimately (to a degree that he could remember and replicate her form). But Nyanko-sensei being the grandfather's familiar (or even just in a similar friendship he has with Natsume) would make a lot of sense. Other familiars have shown attachment to their former masters and their families, and a youkai as powerful as Madara would have to have a very strong bond with an exorcist to agree to be their familiar. 

Also, according to Nyanko-sensei, he has the ability to turn into not two people, but three: Reiko, Natsume, and an old man. Reiko and Natsume seem pretty obvious, but when would Madara have hung around some dude for long enough to have the ability to take his form? It also seems strange that he never takes this old man's form, even when it could be more convenient than Reiko or Natsume's forms. My wild theory is that grandpa knew he was walking into a certain death (maybe a mission to seal a god or something), so he released Madara, asked him to protect his family, and sealed him away so that Madara wouldn't die trying to protect him. Who else would be powerful enough to seal away Madara? The only time Madara has really even been injured is when Matoba caught him by surprise with an exorcist arrow. So not only would the exorcist have to be at least at Matoba's level, but he would have needed some way to take Madara by surprise. 

Alternatively, Madara could have just been close friends with Reiko, but that seems kind of unlikely given Reiko's attitude towards youkai (and that Madara's name isn't in the Book of Friends, although it would be ironic for Reiko's only real friend to not be in the Book of Friends). Having exorcist heritage would also make a lot of sense for Natsume's powers, because on top of having extremely strong spiritual power, he seems naturally adept at a lot of exorcist techniques (such as the shikigami, the paper doll, several youkai capturing rituals, and the contract breaking ritual). Natori does note that it's pretty incredible that he managed to use the paper doll successfully on his first try, and interestingly enough, Nyanko-sensei himself tells Natsume that the contract breaking ritual should be no problem for someone of his power. Having exorcist blood might also explain why Natsume potentially has stronger spiritual powers than Reiko, given that Reiko needed a talisman-covered baseball bat to fend off youkai while Takashi seemed to get by okay until now with just his punches. 

To be honest though, it wouldn't really surprise me if Natsume turns out to have some youkai heritage. The fact that Matoba's paper handcuff seals work on Natsume is pretty strange, and Natsume's weird immunity to fall damage could definitely be explained by youkai blood (which would thoroughly amuse me). 

Maybe Takashi's grandfather was someone really powerful, not sure if he was an exorcist, maybe he came from an exorcist's family and or has youkai's heritage in him which he transpassed to Takashi; I'm not sure he was an active exorcist because the Blue Dragon remembered him with some kind of kindness, and most, if not every youkai never remembers any exorcist with love or nostalgia.

I believe that Reiko and him someday somehow found each other and he might have taught her some things to deffend herself, also I think he was much like Takashi when youkais were concerned: that is to make no difference between them and people, he ovbiously liked youkai a lot and that was why he was invited to Mr. Hazoaki's parties in which many youkai went to have fun... anyone who hates youkai like Reiko would not go there; This leads me to think that maybe Reiko found herself disapointed about this fact and left him (considering her sometimes stupid behaviour-sometimes mentioned by Madara) and that is why Takashi has her last name Natsume, also that Reiko never told her boyfriend/husband that she was pregnant and had her baby all by herself when a teenager (?) Maybe.,,,because everyone, even Madara only remember her when she was that young, and maybe she died when birthing her child... who knows... That can also explain if he was still alive why he never looked for his child or grandchild (never knew he had one)... or maybe he is dead or literaly living under a rock!

Until the author says otherwise I'll believe Reiko abandoned Takashi's grandfather because he was kind to youkai while she hated them... Stupid her if she did that, she denied her child a family besides cursing them with the Book of Friends.

Is hard for me to believe Madara to be relative to Takashi, he obviously formed a bond with him and cares for him more than anyone else so far using as an excuse (that not even Takashi believes anymore) that he only want the Yujinchou... please... he's more his "cub" than "prey" as he practically adopted him!

Besides youkai can bond with humans when looked stright in the eye as when it happened with Taki and that white/furry youkai that entered her house by accident; there he explained Takashi why they never inteact with humans and his now utter need to be close her, to protect her... just as Takuma's shiki, the old woman Ginro said she missed her master to look at her again in the eye... and Takashi always look into Madara's eyes just as he does with Takashi and those he suspects may hurt his 'cub'

Also, can you imagine what might have happened if Takashi, when just orphaned, would have been adopted/taken by the Matoba clan?

I wonder when would the next season or volume of manga be announced...