I am unfamiliar with the BTS universe, so this is my unbiased review.

Firstly, regarding the storyline:
The story is compelling; it revolves around the friendship and struggles of seven teenage boys. However, the writers have chosen to subject the characters to a wide array of struggles imaginable. . This trend continues for the other characters as well. It feels excessive and like they've pushed the boundaries of trauma depiction. They could have balanced this with more moments of joy cause the way the story progressed it seems that whenever they gather and enjoy themselves, something unfortunate occurs in the next scene.

Secondly, concerning the characters:
All the characters are well-developed with unique personalities, and I genuinely appreciate each one of them. However, some characters weren't explored adequately; instead, the focus seemed skewed towards others. Surprisingly, the main character, Hwan, had limited screen time. I felt characters like Dogeon, Jooan, Hwan, and Hosu were underexplored.

Dogeon's screen time primarily revolves around his financial struggles and conflicts with his mother, with limited interaction with other characters. I wished for more depth in Dogeon's portrayal.

Jooan's decision to live with his father rather than his mother could have been explored further to understand his mindset, particularly his attachment despite the abuse—a sort of trauma bonding aspect.

Initially, Hosu played a prominent role, especially with his abandonment issues, but his character development abruptly halted.

I understand others may disagree, but I believe too much screen time was devoted to Haru without significant progress in his condition. His scenes felt repetitive, and similarly, Jeha's storyline—competing for his father's affection vis-à-vis his stepbrother and his troubling fixation on Cein—became tiresome to watch.

Cein's scenes mostly involve brooding in the burnt house or unsettling interactions with the principal and his father, which, while intriguing, felt somewhat disconnected.

I'm not suggesting that their screen time should have been redistributed, but rather that some of the series' mysteries could have been addressed or at least acknowledged. I've heard there may be another season, but without addressing these mysteries, it's hard to maintain audience interest, even if it's setting up for something significant.

In terms of execution, there are flaws, but I appreciate the non-linear storytelling approach and the episodes starting with each character's involvement in the fire. It added an intriguing layer of mystery to the series. Literally none of the mysteries were solved except Haru's.

Overall, despite my mixed feelings about the series, it has its strengths and weaknesses. I hope a second season will provide answers to lingering questions and do justice to this promising storyline.