I'm not going to dive into the show as a whole, plenty of people have already done that. Instead, I want to talk about the throuple in particular, in case anyone is debating to watch the show because of it.

First of all, I want to say that I applaud the show for actually including something that isn't your standard monogamous relationship. Throuples are a real thing, and they are in desperate need of representation. This show is a first step in a long journey, and I'm very glad of it. I've seen my fair share of Thai BLs at this point, and I've never seen this done before, so props to Deep Night for trying (No, I'm not counting Unforgotten Night because that was basically just a threesome without any build up or follow up, so let's not talk about that trash fire of a show).

That being said, I don't think the throuple in this show was done very well. There were interesting ideas, but the execution just wasn't it. Granted, they were the side characters of an 8 episode show, so it's not like there really was much room to explore this relationship to begin with. I think that was the first mistake. If they were going to tackle this right, the show needed to be longer with more room for development of this romance.

Let's dive into the different dynamics of these three guys, shall we?

So, first you have Seiji, who is basically the focal point. He's been best friends with Ken since they were kids and Ken has a major crush on Seiji. I think Seiji is also supposed to have feelings for Ken, but I honestly couldn't tell until he agreed to the whole throuple idea - but I think that's just because the actor was doing a poor job at depicting any semblance of chemistry. Which was part of the downfall, but anyway... So, Seiji and Ken are best friends and everything's great until Japan shows up. Seiji and Japan have a strong case of insta-love - meaning that they like each other for no discernible reason at all right from the get-go. However, Seiji plays hard to get (Assumably because he has feelings for Ken too, but I only know that now in hindsight. While watching the show, I was confused why he didn't just go for Japan, but again, bad acting paired with unclear writing). With Japan coming into the picture, Ken suddenly decides that it's now or never, and the two of them begin to compete for Seiji's love. Which ultimately results in Seiji kissing Japan, thusly making his choice, and them beginning to date. Ken is heartbroken and walking around all sad and dejected. Japan is feeling guilty over the whole thing and Seiji feels bad about it all too. Again, I assumed Seiji was feeling bad because he hurt his best friend, not because he actually likes Ken, but I digress. Japan talks about feeling guilty, leading to his friend joking about how they could always have a threesome. Japan then fantasies about said threesome which came completely out of the blue. And funnily enough, in his imagination, both other guys are basically focused entirely on him, rather than Japan and Ken focusing on Seiji, who's the one they both have feelings for. This left me confused once again, because I assume this was the writers' attempt at showing that Japan kinda has the hots for Ken or likes him or something, but it was done so poorly that it just left me feeling very wtf-ish. Anyway, after his little fantasy, Japan proposes to Seiji and Ken that Seiji could date them both. Which he definitely should've discussed with Seiji first, before mentioning anything to Ken but oh well... Japan says that Seiji having two boyfriends means double the care and double the happiness (It would also mean double the issues, but I won't ruin their fun). Ken agrees to this, and Seiji - with all the enthusiasm and emotion of a depressed piece of toast - does too. Alas, the throuple is formed. They have a group hug, and a few cute montage scenes. The end. No kissing, not actual threesome, nada. Just a lot of unanswered questions and frustrations.

Basically, during that scene of Japan proposing the throuple idea, we were led to believe that it's going to be both him and Ken dating Seiji. There is no talking about Japan and Ken also being romantically involved. Which was the biggest point of confusion for me, because of his threesome fantasy and because in one of the final scenes, Japan and Seiji both offer Ken some food - a nudge to a past scene where it was Ken and Japan fighting over whose food Seiji picks, a very unsubtle allegory for having him choose one of the two. So, maybe over time Japan and Ken developed a romantic bond too? Or maybe they didn't. I guess we'll never know. We'll never know at what point Seiji started to like Ken either. They had some moments, but it always seemed like Ken was the only one interested out of the two. Again, a mix of bad acting and bad writing I assume...

None of this is great, but it's not the worst thing I've ever seen. The biggest problem is how frustrating it all is, because this could've been SO good. They had all the ingredients, but somehow managed to bake it into something that is confusing at best and nonsensical at worst. Now, allow me to tell you how I think the entire thing should've gone.

Have Seiji and Ken be childhood friends. That was all well and good. So was Ken being secretly in love with Seiji. None of that needs to change (other than swapping the actor of Seiji because that guy had no chemistry with either of his romantic partners and no emotional range). Then, Japan comes into the picture. But instead of him being completely new to Seiji's life, have them know each other from the start. Maybe they've been friends for a while, but Japan went to study abroad and now he's back and they reunite. That way, it won't feel as insta-lovey, because they already have a bond. So, Japan comes back into Seiji's life after a while. They both have changed, grown, and matured. They catch up, notice how the other has changed, and they begin to fall for those new sides of each other. Ken realises that Seiji is spending more time with Japan and starts worrying. Things get tense when Seiji brings Japan home for dinner and the three of them have a meal. Seiji goes to the bathroom and Japan and Ken basically tell each other they're in love with him. Thus, the competition for Seiji's heart begins. Seiji is kinda enjoying this, because he obviously likes Japan and seeing him fight for him is something he finds cute But also, seeing Ken be this serious about winning him over is kinda stirring something within Seiji. Something that wasn't there before.
While competing for Seiji's love, Ken and Japan somehow get forced to spend more time together. Maybe when they go on their little getaway trip with their friends, they fight over who gets to share a room with Seiji. Eventually, their friends get fed up and put them in a room together while Seiji rooms with someone else. During that time, Ken and Japan get to know each other better, and would you believe, they somehow start realising the other isn't so bad. In fact, they start finding each other kind of cute and suddenly... What is that?... Oh, they start falling for each other too! Of course, they don't know that about the other person, so it's angsty and a lot of silent pining. Ken realises that now, he wants both Japan and Seiji to be happy, so he backs out willingly and gives them his blessing to be together. So, they kiss and are now dating.
But something feels off. They get all weird as soon as Ken is around which leads the two to have a talk. Seiji admits that despite being head over heels for Japan, he also has feelings for Ken. In what is the plot twist of the century for Seiji, Japan admits to also having feelings for Ken. Suddenly, things start clicking in Seiji's head and we get a slide show of moments between Japan and Ken that Seiji hadn't really noticed before, and he blurts out "I think he likes you too!" And thus, they decide why all the heavy hearts if there's a simple solution to the issue. They sit down Ken and Seiji is basically like "I like you. Japan likes you. I know you like me. And I know you well enough to know you like Japan too. So... What are we doing? We should all just be together." They have their little group hug and then they make things awkward when they want to kiss but aren't sure who should go first and all that jazz. It's cute and embarrassing and eventually, they get the hang of it. Throw in that threesome scene if you must. Have a cute montage of them bonding and being all happy together. Then add a special episode where they figure out their different dynamics and boundaries and all. And so, they live happily ever after. (It would be even greater if they explored the difficulties a throuple brings as well, but I don't trust these writers to handle that well, so I think it's best not to go there at all...)

If they would've done it this way, I would've easily rated this an 8 or a 9. However, with the clunky writing and the poor acting/chemistry, this storyline is only a 6. And even that is kind of generous, but I gotta praise the attempt at least. I think out of everyone, the guys playing Japan and Ken had better chemistry than either of them did with Seiji's actor, which wasn't really helping the narrative... Maybe if Seiji had better chemistry with Ken, things would've been a little less confusing, but I guess casting attractive people over actors with actual skills is a growing issue...

Despite its flaws, would I still suggest you watch this? Absolutely. Not because it's great, but because if people are rooting for this throuple, there's a greater likelihood of us seeing more throuple storylines in the future. Hopefully ones with better writing and chemistry. And one day, we'll get an actually great one. I'll be here, waiting.