Isa-ssi

Why I am so sad when hearing this song :(

If I am not mistaken, Hee Yeon and Ji Hyuk have different mother. Hee Yeon's mom is Ji Hyuk's Dad second wife

Episode 5 is way too good and beautiful. And as usual k-drama, that beauty is leads to a problem aka the ex-problem. I hope Moeun and Jinwoo will keep going strong and even strongerrrr!

I just realized it after reading your comment. At first, I thought Pyeon Sang Wook was a spy haha

Yu Chan is definitely deserves better

The best thing of this drama definitely about the patient's story. I am not fond of the main couple's romance, I think they lack chemistry (?). I don't know, maybe I am biased because I am sad to see Song Yu Chan as a sad boy. But in the end, when Yu Chan is having a hard time in his new office, but Da Eun is too busy with her new bf, I think Yu Chan is deserves better. Looking back to their long-history-friendship, I hope Da Eun with at least come to Yu Chan's house or message him and ask how's his adaption process and his anxiety attack. I hope someday, Yu Chan will meet a girl who loves him deeply and would give him a reason to stay alive, just like how he tried so hard to watch a drama for Da Eun, even if he never likes it from the first place.

I actually like the second couple better than the main one.

But it's not like the FL cheat with SML. She and the ML is already break up years ago

Because it's triggering for people who has suicidal issue

Nam Si Heon is the straight one, and the REAL Koo Yeon Jun is the gay one. So, the Koo Yeon Jun that dating Han Jun Hee is actually Nam Si Heon soul in Koo Yeon Jun's body.

Me too! I actually feeling very smart for understanding the plot with no problem at all hahaha

The FL is Han Jun Hee. Kwon min Ju is SFL. While the ML is Nam Si Heon. Koo Yeon Jun is just a support role.
So in the end, FL ends up with ML. And SFL ends up with SML.

It happened a lot in time traveler's movie. As long as they in two different bodies, even if only there's one soul, they can still met and communicate.

For me, it's a happy ending :)

Live happily with Minju in the end of the story.

Yes! It gives the same vibes with Dark just a little more romantic. And if you already used to watch Dark, this ATCY's plot is so easy to understand.

I hope my explanation in the previous answer will help you to understand

Thank you for your explanation. Let me make diagrams for it so it will easily to understand.
1998: Nam Si Heon is 18 y.o.
2002: Nam Si Heon is 22 y.o and got into bus accident, time travel to 2007
2007: 22 y.o Nam Si Heon woke up in Koo Yeonjun's body. Yeonjun is 20 y.o, and presumably died so there's no Koo Yeonjun's soul.
2008: Nam Siheon in Koo Yeonjun's body seek for Han Junhee. Got into same university and become a couple. Use Koo Yeonjun's identity.
2022: Nam Siheon got into airplane accident, and his soul travel back to 2002.
So, the one who woke up in Si Heon's body in 2002 is not 22 y.o Siheon, but mentally 37 y.o Nam Si Heon who already live in Yeonjun's body since 2007 - 2022.
I hope this explanation is easy to understand.

Actually, I think you should watch more time traveler's movie or series. Because, in time traveler's genre is happens often one person's soul can communicate with her/himself in difference body. So, even if at that time is only one soul (Nam Si Heon), but because there's two bodies (Nam Si Heon and Koo Yeon Jun), they can still communicate. Yes, it's doesn't make sense in real world, but it can happen (and mostly happened) in time traveler's movie or series.

Koo Yeonjun is never meet Jun Hee or fall in love to Junhee since the very beginning. After his accident with Tae Ha in 2007, Yeonjun is died and his body is empty. Who lives in Koo Yeonjun's body in 2007 is Siheon from 2002. So, Siheon got coma in 2002 and his soul went time travel to Yeonjun's body in 2007.
And for your statement, "Koo and Jun might never become a couple." It's true. Yeonjun and Junhee never be a couple. Yeonjun never meet Junhee. The one who greet Junhee in the bus in the ending of episode 12 is Nam Siheon, not Koo Yeonjun.
But I think your statement that "Koo might never had the car accident" is wrong. Because, the original Yeonjun accident is not related to any of time traveling plot. Even if Junhee never back to 1998, Yeonjun is still goes to accident. The only difference is, after the accident, his soul will left his body and there's no Siheon will got inside Yeonjun's body so we can assume, without time traveler, Yeonjun will died with Tae Ha in the accident.
I don't get with "The body switching of Young / Hee doesnt' make sense." Who is Young and who is Hee?

Which part make you confused? Maybe I can help. So, about Nam Si Heon's time travel ... in 2002 the original Nam Si Heon got into traffic accident after he visit In Gyu in jail. And his soul woke up in Koo Yeon Jun's body in 2007.