gatalito

They know it because they heard him replying to his mother in law at the 62:37 minute of the first episode when the teacher goes to fetch his mother's in law hat from the car. The kids are sitting next to his car. The mother in law says that the hat is at rear seat and the teacher replies "I've got it mother in law". (though it is not translated in English).

I don't think so. You can't prevent babies from interacting with strangers. This is something that they will have to deal for the rest of their lives and even if they cry when they are very young because they get scared, in time they get used to it, as we all did after all.
Babies have irrational fears but as they grow up and get over them.
My younger sister when she was a baby she was crying her eyes out for any imaginable reason. She was scared of strangers, the sea, cars, dogs, cats, even the sound of her spoon knocking on her plate. Now she is doing bangee jumping and she is travelling abroad all alone.

My comment wasn't aggressive. Sorry if it looked like this.
But after finishing this drama I took a look at the comments and I saw a completely different version of this drama. A whole conspiracy alternative plot that I wasn't able to detect anywhere! And then I read your comment saying that you didn't see the one or the other thing that supported this alternative version of the plot and that is why I ask you if you are hallucinating!
Of course you couldn't see anything because it wasn't there in the first place to see it. And I don't know where those who made the videos saw all those supposedly hidden clues that could support an alternative ending with the ML dead or killed afterwards.

Even if the girl was able to hold herself for a few moments out of the window Chao Yang wouldn't be able to save her either way because he was further away and she fell suddenly out of the window. He went to the edge of the window but she had already fall. And that is what Pupu said. She fell.
( children are very good on stating facts after all! )

As I've said on my previous comment I wasn't sure either if Pupu died or not because we didn't see if the ambulance went at the teacher's place in time.
But this doesn't change that much in the plot.

But I'm more than certain that the other two were alive up until the end because they gave their statement to the police. Chao Yang dry and splattered with the blood of the teacher and Yan Liang wet to the bones with a white towel on his back.
You can see it at the 25:34 minute of the 12th episode. And it was his uncle who grubbed him and took him out of the water. So he wasn't dead either.

There isn't something in this drama to support any alternative version of the story.

The babies cry because they have to interact with people that they don't know. ( the actors ).

Where is that? Can you give me a link please?

They were all very alive at the end. I don't know who came up with the conclusion that they were dead.
The reason why I believe that they were alive at the end is that Yan Liang gave a statement at the police station, wet to the bone but very much alive.
Also the secret that Pupu hold for Zhu Chao Yang wasn't that he killed his sister but it was about being present on the fifth floor the day that she fell all by herself that he kept denying it up until the end. That is what Pupu told him to do. To tell the police that he was present and not that he killed her.
He didn't push her out of the window. She fell herself when the desk or whatever was that she was standing on broke. You can see that at the 9:40 minute of the third episode. Check it out .

Are you hallucinating? I've just finished this drama and his younger sister fell off all by herself . The desk or whatever was standing on, broke she missed her step and fall out of the window. The moment that it shows the broken desk is at the 9:40 of the third episode. She was not pushed by her brother and he was further away to be able to catch her.

Yan Liang wasn't dead at the end because he is shown to give a statement to the police station along with Chao Yang, wet to the bones but still there with the whole police department present.
As for Pupu I don't know if she survived but both of the boys didn't look like she was dead and we saw that the killer teacher called for an ambulance so she probably survived the asthma attack.
The teacher killer didn't kill children for the sake of doing so. He killed his in laws because he thought that they interfered to his marriage and finally his wife because she was cheating on him and he couldn't deal with the fact that she was about to leave him for another man.
That is also the reason why he protected the children from Wang Li, that he killed him while they were fighting. This wasn't intended. The teacher didn't kill randomly because he was completely psycho. His motive was his obsession with his wife.

As for the final scenes that probably confused you both had very logical explanations. Pupu said in her letter to Chao Yang that he had to reveal that he was present there on the fifth floor something that he was denying from the very beginning and particularly after the bullying that he got from his father's wife and the other scene with Yan Liang at the school was all about his loneliness.

They were all alive at the end and I don't know how you ended up to the conclusion that they were dead and they were interfere with the killer as ghosts.

She is a very talented little girl but isn't she too young to work so hard in this particular industry? Children should be allowed to live as children.

I've finished but the end was a complete and utter let down. And that because those who straggled that hard to bring this case to justice were punished way to severe for what they did.
Both the Justice system and the Police failed to protect them from this company's gang methods. The journalist in particular, got two years in jail for not reporting the murder of Hou Gui though there was no one to report it to, by the time that the police and the authorities were so corrupted.
Let's not forget that the Yellow Hair guy was arrested and released twice while Hou Gui Ping was murdered a few hours after he announced that he intended to report the rapes and the murders to the police.
So Zhang Xiao Qian did the wisest thing ever when she changed her named and disappeared from the area even though she had witnessed the murder of Hou Gui. Who could blame her for not reporting it when even as an adult and supposedly protected witness was almost killed in the tunnel assault? She was the only witness who survived due to her own efforts. Not because someone protected her. It was the system in this case that let all these people down and not the people that didn't comply with the system.

Anyway.. the whole drama is full of preaching about how much the police is supposed to care and protect the people, but at the final episode it passes the exact opposite message. The policemen were rewarded without actually solving with their own means the case and those who actually revealed this case were punished along with the criminals, instead of getting a few years in probation. And I 'm saying that that because the policemen had at the end of the day the obligation to bring this case into justice and not the reporter, the lawyer, the ex policeman and the medical examiner. It wasn't their job to catch the criminals but they did so either way.

8 out of 10 from me I was going for 7 but I give them one more point for the great acting and cinematography and the good story that unfortunately was spoiled by the constant and vague flashbacks.

Very good drama ( though I haven't finish it yet) but this back and forth in the story plot between the different years without indicating the dates is confusing and extremely tiring. And that because they haven't manage to distinguish clearly the different years by the clothes or the cars or even the appearance of the characters that don't seem to age even though the case goes on for more than a decade.

Perhaps the kid is the inventor of the Grid. It is after all about two generations younger than the Ghost.
But then again this is not very valid option because the kid would have been still alive in 2021 in the normal world.
It is not after all that the Ghost went back to the past in order to save the kid that it invented as an adult the Grid. She went back to install the Grid. So it is a technology that there was no chance to be developed in the "present" world ( 1997-2021 and onward with or without solar flare).

It doesn't also make sense the murder of the janitor. The Ghost ( as long as it was present and wasn't disappeared ) killed the janitor after she had installed the Grid. She installed the Grid and then she went out to kill the janitor in order to prevent him from taking the kid out of the building.
When she was delayed and didn't have the time to make the installation and prevent these two from getting out of the building she disappeared. And from this point and on didn't reappear.

There is also another thing that doesn't make sense that I mentioned earlier. That the transport device is still the same. I mentioned previously that Sae Ha took the Ghost's device. So the scene were they are both present on the same time line with the same device is a bit off because the device can't be duplicated because it is the mean to make the time travel. If the device was duplicated then there would have been infinite numbers of devices. Everyone and anyone that could steal the Ghost's device s/he would have had then it's own device.
It doesn't make sense to see each and everyone traveling in time with the same device and the same implant and meeting the others that have the same device and the same implant in the same timeline. Because it the device is allowed ( by any time travel law) to be duplicated then the persons would be duplicated too just because they traveled to the same time line from two other different timelines.

Thank you for the suggestions. I will check those too. :)

If it is just 12 episodes I'll watch it.
The reason why I don't watch C-dramas is the number of episodes that are most of the times countless.

Ha ha ha haaaaaaaaaaaaaaa...
Do you know what is printed on Shinkai's sweater on the beginning of the 2nd episode? It writes that he is a jerk in Greek. ΜΑΛΑΚΑ means jerk or as$hole. loool

This is not a good print for a sweater or a T-shirt. The word is used as an insult or in the best case derogatory.
Let's hope that this sweater didn't become a trend in Japan! ha ha ha ha

What makes him so popular and successful IMHO is his casual way of acting and his "next door guy" appearance. You never feel that he is acting because he does so, so naturally. His acting is never over the top, it is just cool and natural. And you lose completely the notion that he is an actor because his appearance is not something so extremely perfect to separate him from the average viewer. You can easily identify with him and that is the reason why he is so persuasive in his roles. And that is also the reason why he is so good on setting trends and selling products.

No Ghost = no Grid
And no kid= no Ghost
which bring us to the conclusion that
no kid = no Grid!
It reminds me the Logic lessons at high school! lol

I didn't miss any part of it. If the world had no Grid those who survived and were affected by the radiation wouldn't be able to have children in the first place.
Also I didn't say that it doesn't matter if one of her parents is killed but that it doesn't matter WHEN one of her parents is killed. Either way she wouldn't be born.
The final result would be the same.
That is the reason why I said that she probably is a product of the non destroyed world. She is two generations ( each of 25 years) forward. So yes... technically if the kid is related to her is a grandparent and not a parent.

You belong probably to the rare exceptions. But either way you can't inherit a negative blood type from two positive parents. So if you ever need blood the first donor would be your mother. And if she can't give you blood then it would be her siblings or her parents.
The first persons that are asked to donate blood, particularly very rare blood types, are the close relatives.
It also depends on how "difficult" is your blood type. Yours is difficult because you can donate blood to anyone with Rh negative blood type, but you can get blood only from your blood type.
I have the rarest blood type, I can take blood from anyone with negative blood type but I can donate only to people with my blood type. ( which hopefully are very few).

Even if that is the case and the child was one of her parents then failing to install the Grid would have had the exact same result. Her parent would have been killed later on 2005 when the solar wind destroyed the world.
Does it really matter when exactly one of her parents was killed?
The story up until now is No Grid- No Ghost in 1997.
But we do know that she got back in 1997 and that is where the paradox lies with or without the contribution of the janitor's kid ( or whoever's was that child.... " Billie Jean is not my lover.....and the kid is not my son.... " ha ha haaaaa...
Sorry for laughing but I can't it seriously anymore!

I don't see how the Ghost lady's existence could be related with the Janitor's and Sae Ho's father. The third time after all that Sae Ho went back to 1997 to reverse the results of his second attempt ( where the Ghost disappeared) she wasn't any more there and his dad was killed ( that was in the finale of this episode).
So her disappearance due to the fact that she failed to install the Grid was definite. She has gone from 1997 and his father was killed either way.