Well it’s more of I was convinced at the hints on the theory of All For One is Izuku’s father thing (This is the link btw: link)

To answer your question: I’m up to date to the manga especially chapter 198 :)

So, the first thing that really made me curious was this picture. The side by side of Izuku and All for one is just too similar that it’s uncanny and it made me wonder. Could they be related somehow? 

(So I have to look for the subtle hints on the manga. and all the subtle hints are on the link above )

We all know that Hisashi Midoriya…

• Works Abroad
  
• Has a fire breathing quirk 
  
• His name means “It’s been a while that I’ve seen you” or “a long time ago”

We don’t know much of Hisashi other than those info.

But I could say that they all checkout.

1.) Hisashi works abroad… Meanwhile we see All for one is in America in this panel.

2.) Hisashi can breath fire. Meanwhile All for one has multitudes of quirks that there’s a possibility of one of those quirks is fire breathing (He could have lied to Inko on what quirk he truly has. He is not careless to just say it bluntly to Inko ‘Hey I have a vast amount of quirks) that would be ridiculous.

3.) Hisashi’s name. Horikoshi has a thing of puns in the names of each of his characters and it’s awesome and cute. His name just means ‘a long time ago’ meanwhile All for one is ancient. He was been here since the beginning of quirks appear in the world.

Some speculations that I really like and that made sense in a way.

• If All for One is Hisashi, it just made sense if Izuku is quirkless. Since All for One is from the first generation. The chances of having a baby to pass on the genetics of having a quirk would be super low.
• If by chance. Izuku has a quirk. It would also made sense if it’s subtle since we all see that All for one’s brother. One for All, also have a quirk but it’s not that noticeable maybe it’s in their genetics like in the family of some sorts.
• Deku’s doctor seems to look like the same one as All for one’s doctor

The possibility of him altering Izuku’s test result is super high. I kind of noticed that Inko and Izuku only checked up on this doctor and they seemed didn’t go to another one to have another opinion on the matter of Izuku being quirkless or not 

(Aside from that, the voice actor for the doctor is the same as the voice actor for both of them 

• We all know that All for one wanted to kill off all the One for All’s successors. The only troublesome quirk that he couldn’t take back and also be stolen. He is brutal and unforgiving as you can see  how he dealt with Nana. 
  

He blew up he entire city just to kill Nana (that’s just overkill! But then again, He locked his sickly brother in a vault so…

All for One has a lot of connections. He will know where Yagi Toshinori is because he knows he is the next successor next to Nana. He will hunt him down and kill him off for sure. that is why Gran Torino is hiding Toshinori as much as he can. He protected him through out the years.

Though that made me wonder…

Since we all know that he wanted to kill all the successors. Especially All Might. And WE all know that All for one knew of Izuku was the next successor. Then why didn’t he kill him off back then in the Kamino Ward?

He is brutal, unforgiving. He even overkilled Nana and will kill All Might. Yet why? These 5 students (especially Izuku) were just hiding behind a broken wall and he couldn’t see that? It is super convenient that there’s a wall part that isn’t even damaged and it is enough to cover the students.

Why is there a hesitation on his part? He can see them. He knows that they are there, yet why didn’t he bother to finish them off just the what he did on the other heroes?

Not unless something is holding him back…

Also in other things. 

• The way Izuku’s One for All activates. Red is the symbol of All for one and Light Green glow is for One for All.
  

Yet we see them on Izuku. The red lines and the lightning. Could be that he has a remnant of All for one’s quirk in him, a mutated version of it?

• Then there’s this part where he can communicate to One for All…

Yet we don’t see ‘just’ One for All’s memories. WE also see All for one’s memories…

As you can see here…

One for all isn’t present at all and we know that he is sickly and we all know he is locked up in a vault and he would never joined in side by side with his brother to see this.

It is strange… why would Izuku would ever have those memories…. Not unless… he has a remnant in him of All for one’s quirk…

• We all know of the star wars reference, you can look up the link from above earlier to further the details.
  
• Then there’s this part:
  

Translations are different on this part as I heard and this lines are super vague compared to the volume book release. Yet in the other translations, it is not stated what All might took from him. It could be ‘what he has build in like his empire yet there’s the part in the translation of he took something or someone from him. It is vague but I want to believe that it is so dear to him that he has to kill All might for it.

REMEMBER, He locked his brother in a fucking vault for heaven’s sake. He is possessive, even what he is doing is wrong, he always thinks what he think is the right thing to do. He locked his brother to either protect him or for him to just not run away, to keep him there.

• I would like to also point out something and credits to everyone in the All for one servers that I’m in to point it out:
  

Horikoshi said in his latest interview that ‘Izuku’s father will be ‘revealed’ soon in the manga’ let’s point it out. It is said ‘revealed’ and not ‘introduced’ which just saying that we know the character in the manga already and it’s super exciting!

To those who are curious of the interview here’s a twitter post link here from Viz Media: 

(https://twitter.com/VIZMedia/status/1021116156885680128/photo/1)

More links: (https://comicbook.com/anime/2018/07/22/my-hero-academia-creator-deku-midoriya-father-tease-manga/)

The timing of that interview was perfect that the week or so after the interview. We got the One for All dream.

So yeah, I’m pretty convinced that He is Izuku’s dad