So if you finished watching Tale of the Nine-Tailed, you know that Lee Rang died for Lee Yeon, his older brother, to reincarnate. Lee Yeon died with the real Imoogi host inside him and Terry. He jumped in the Samdocheon River. If you jump in the Samdocheon River, you'll NEVER get reborn nor reincarnated again.

1. Lee Yeon getting reincarnated in an adult body
Based on research, the difference between Reborn/Rebirth and Reincarnate is - Reborn, you'll be born again in a new body whereas, in reincarnate, you'll be born again in another person's body. And Lee Yeon got REINCARNATED, not reborn. Which explains why he saw Nam Ji-ah in his old body. But, why did Yeon remember all the memories from his past life? Some kids say they remember their past lives, which might be the case for Yeon, but still might not explain why he remembers everything.

2. Is Yeon still a fox or a human?
If you watched the press conference, Jo Bo-ah (Nam Ji-ah) gave the advice to do some research before watching the drama to make it more interesting. You can also research AFTER you've watched the drama.
Yeon is STILL a fox. He transformed his red umbrella into a sword, and his eyes changed NOT because he transformed into a fox, but because he was reincarnated AS A FOX. At the end, when Ji-ah found Yeon, Yeon told Ji-ah he's finally a human, which is NOT TRUE. But why did Yeon lie?
Based on research, a fox can be turned into a human IF the fox marries a human and the human doesn't spot them as a fox. If they do, the fox has no chance of becoming human. And Yeon's wish was to become human, which explains why he lied. Also, when they were discussing having a baby, Yeon said something about a daughter. It's because he's still a fox, and foxes can see the future.
In the first episode, the fox sister was also going to get married to a human, and while Yeon was with the fox sister, the fox sister begged Yeon to spare her because she "WANTED TO LIVE AS A HUMAN". It was more of a clue rather than to give confusion to the viewers.

3. Lee Rang being reincarnated as a 10-year-old boy
In the end, after Yeon and Ji-ah were happily married, Yeon saw Rang in a REINCARNATED (not reborn) version in a 10-year-old boy's body. Again, reincarnated is being born again in another person's body. And when Yeon saw Rang, it was 6 years after, according to the viewers. (I don't know how they got the information, but maybe someone in the cast mentioned something). It would've makes sense if Rang was in a 6-year-old boy's body, but it's REINCARNATION and not rebirth which explains why he's in a 10-year-old boy's body.


MY OPINIONS:
There were a lot of confusing scenes even I couldn't explain, for example, Ji-ah's parents going to the island. On my POV, Ji-ah's parents went there for the same reason as to why Ji-ah went there. To know why women are mysteriously disappearing on that island. But it still confuses me.

PLOT
Tbh, the plot was kind of confusing. As I said, there are a lot of confusing things in the drama. The plot is "an urban dark fantasy drama about a gumiho who settles into the city and a producer who is after it." At first, it was really enjoyable not until episode 10. Things became more cheesy and I'd prefer Yeon and Ji-ah stay as friends. (Because not all soulmates are lovers) In the beginning, Yeon's job was to lead the other creatures to the underworld in exchange for A-eum's reincarnation which happened 600 years later. (Taluipa said that a Reincarnation is a random event)
Let me get straight to the point, there are a lot of unsolved mysteries in TOTNT. The reason why Ji-ah's parents went to the island was never explained and I'm still confused until now even after 4 months of watching it. I've rewatched the drama 2 times already and still couldn't understand why Ji-ah's parents went to the island, though I gave my POV. There was a lot of action scenes as well, like for example the scene in the Forest of Agwi (I think that's what it's called but I forgot HAHA) which excited me so much!

CHEMISTRY BETWEEN THE ACTORS
Main Pair (Lee Dong-Wook and Jo Bo-ah)- IMO, their chemistry satisfied me haha. There were a lot of unreleased behind-the-scene clips of TOTNT, so I guess we weren't able to see other things that happened on set. (I saw some unreleased clips on Instagram hehe) The chemistry of the main pair was quite great and until now I'm still thinking about it (HAHA) They shared (a lot) of sweet moments (IMO)! Also, LDW loved to tease JBA which was very cute! They also sent food trucks to each other both in January! (JBA sent a food truck to LDW at Jan. 12, 2021 and LDW sent 2 food trucks to JBA at Jan. 10, 2022!) They also BOTH sent food trucks to Kim Beom (LR) to support him for his new drama "Law School" last year, January 7, 2021, as well, and they also sent a food truck to their PD! Their chemistry was also showcased greatly in their interviews! (1st Look, Dazed, tvN interview) IMO, the scenes wouldn't come out great if their chemistry wasn't great. (I mean, In my POV, they're very comfortable with each other)
Second Lead Couple (Hwang Hee and Kim Yong-Ji)- These 2 are also a great pair! The more you see them, the better you'll think they'll look good! These two's chemistry with Soo-oh (Blacky Reincarnate) is also great and shows proper family chemistry! Soo-oh was also very cute haha! They did a reaction video and that's where I saw 2 of the unreleased behind-the-scenes clips! Their chemistry was also great in that video and their reactions were very cute!! (IMO)
Bromance (Lee Dong-Wook and Kim Beom)- The bromance here was very good as well! LDW loves to tease KB (And recently, even gave him a food truck yesterday, January 23! It was very cute, haha, and KB thanked LDW on his Instagram Story, which means these two gumiho brothers are still in touch) I don't have any complaints about this bromance, the bromance was very good ngl and I would love to see a bromance compilation for these two!
Cast Chemistry (Lee Dong-Wook, Jo Bo-ah, Kim Beom, Hwang-Hee, Kim Yong-ji)- The cast chemistry is really good! The cast became close friends and are really comfortable with each other! (My POV & Opinion) If you've seen the behind-the-scenes, their chemistry would have been pretty obvious especially with the main leads! LDW revealed that them three (LDW, JBA, and KB) are mostly together during the set! There are also interviews for the 3 main leads and you'll see their sizzling chemistry! (Press Conference and Interview during the day of the premiere, if you want to watch it you can search it up on YouTube!) KB and KYJ even have an interview of their own!
THESE ARE ALL JUST MY OPINIONS!

CAST
Lee Yeon (Played by Lee Dong-Wook)- LDW matches here pretty well. His acting is also very good. "If LDW wouldn't do it, who else can?" I feel like LDW would be the only actor who would fit this role! He portrayed the role really good which made me enjoy the role! I like how he portrayed the witty and funny side of Yeon, and his action scenes also came out great!
Nam Ji-ah (Played by Jo Bo-ah)- JBA's acting is really good as well. But I feel like she doesn't fit for this role (?) IU would have fitted for this role IMO. But JBA played 4 characters (Nam Ji-ah, A-eum, Imoogi inside Ji-ah, and Imoogi inside A-eum) which impressed me! (My toxic trait is that thinking I could play 4 characters as well lol) She portrayed this character well too!
Lee Rang (Played by Kim Beom)- KB also matches this role! Gumihos are known to be beautiful/handsome so the two gumiho brothers fit pretty well. His acting was also really good and I was really excited for his action scenes with LDW!
Gu Shin-ju (Played by Hwang Hee)- HH's acting impressed me so much. He's considered as a rookie actor even though his acting was really great. He also fits this role tbh. Gu Shin-ju is Lee Yeon's friend (and right-hand man according to himself haha), and he portrayed the role really well.
Ki Yu-ri (Played by Kim Yong-ji)- KYJ is also considered a rookie actor, even though her acting is really great. Ki Yu-ri is a fox who takes from people, and she played the character really well. She fits in the character too! She's also very beautiful!!
Imoogi (Played by Lee Tae Ri)- Despite being the youngest among the adult cast, his acting was still pretty good and he fits in the role. He portrayed Imoogi really well. I'm really impressed by his acting and IMO, he deserves an award!
Kim Soo-oh (Played by Jung Shi-Yool)- First of all, he is VERY cute! Despite being a child, his acting is really good and I think he'll become one of the best actors in the future! Starting acting in a young age can help him learn more lessons for his future actions. He fits the role since Soo-oh LOVES to play with people. He portrayed all the characteristics and the character really well! Someone give this child an award please???? (Or at least a KitKat!!)
There are a lot of characters but It'll take forever if I put them all here, but all the casts' acting was really good! (All these are my opinion)

THE ENDING
The ending was kind of expected, I expected Lee Yeon would die in order to save Ji-ah because he didn't want history to repeat itself. But Lee Rang dying was quite unexpected in my POV because I thought Ji-ah would die. And also, Rang and Ji-ah both love Yeon so much. But why Lee Rang? The time when Rang had a family and became a better person, that's the time he's going to die? I mean, Rang is on one of Taluipa's WANTED lists, and at that time, Rang was still that evil fox. And plus, Rang is a half-fox. No half-fox could've lived that long.
I could have understood if Rang died earlier when he was still that bad fox, but he died when he became a better person. (It literally made me cry while watching it)
The only complaint I have about the ending is "Why would Rang die at the worst timing?" Plus, I didn't want Ji-ah to die, but why Rang? I don't fully blame Ji-ah on why the Imoogi is inside her, but why would Rang die to save Yeon? Ji-ah was the one that should have died because it was her fault at the start. I would've understood it more if Ji-ah died because it was HER fault. Not Rang's. I really wanted to see Yeon x Rang moments as gumiho brothers..