Glass Heart Review: A Captivating Love Letter to Music

The history of our connection to music goes way, way back. As a cultural universal, music is present everywhere all the time. It conveys emotion, creativity, and culture. It offers solace and encouragement. Since music has existed for almost as long as human beings, it’s no surprise that cinema and television have portrayed this bond several times with different degrees of success. From Japan, we’ve talked about Fuji TV’s Nodame Cantabile here before, but we can also mention TBS’s Fight Song or films such as Miki Takahiro’s Have a Song on Your Lips, Okudera Satoko’s Maestro!, Yaguchi Shinobu’s Swing Girls, or Norihiro Koizumi’s The Liar and His Lover. Stories with and about music can be found aplenty, but I believe music has rarely seen such commitment and affection from a television drama as it does with Netflix’s long-awaited Glass Heart, which came out on July 31st, 2025.

Based on Wakagi Mio’s novel of the same name, Glass Heart is a 10-episode series written by Okada Mari, Akutsu Tomoko, Kosaka Shiho, and Kawahara Anna and stunningly directed by Kakimoto Kensaku and Goto Kohtaro. The story follows the ups and downs of TENBLANK, a young but brilliant pop-rock band as they rise to stardom. Led by multi-instrumentalist singer-songwriter Fujitani Naoki (Satoh Takeru), TENBLANK has Takaoka Sho (Machida Keita) on the guitar, Sakamoto Kazushi (Shison Jun) on the keyboard, and Saijo Akane (Miyazaki Yu) on the drums.

This review is spoiler-free! But if you’re in a rush, why don’t you save it for later? Our pin is at the bottom!

A Glass Tuneful Heart: Storytelling Through Music

A feat of Japanese visual storytelling, Glass Heart is an intense and passionate love letter to music. The universe of Glass Heart is defined by the sounds it creates, whether they be everyday noise, meaningful tunes, or the ticking clock of its protagonists’ lives. Dialogue is kept in the background because it’s through TENBLANK’s songs that our characters truly communicate. Takagi Masakatsu’s incredible score serves as a melodic narrator which frames the story that unfolds before our eyes. The characters’ perception of sound is portrayed through montages and meaningful compositions. The editing and camera movement have a rhythm that beats in sync with the emotions and lives that we’re following.

Music lies at the very core of Glass Heart and makes up its very foundation. That’s why the show shines the brightest during its musical sequences — because these songs are the characters. Their arcs aren’t portrayed narratively but musically: TENBLANK’s songs clearly change throughout the series, going from a more individual to a more communal experience while also becoming ever more heartfelt.

This happens because music is the means through which the characters interpret the world around them, express themselves, and grow. Naoki, Sho, Kazushi, and Akane (and I’d also add Suda Masaki’s Shinzaki Toya here too) come together as four completely different individuals who have to discover their own sounds in order to unite them into a rhythm that represents them as a group. They are four broken souls who have been exploited, rejected, but most importantly, misunderstood — and it’s through their music that they can explore who they are and who they want to become, finally being able to tell the world what they really want to say.

Beyond serving as a means of expression, music is also a vessel for connection. We respond to music almost instinctively and find in it the comfort, company and understanding we seek. Our favourite bands bring us closer to our peers — people with whom we not only share the same taste but often share the same perspectives, joys, and sorrows. The members of TENBLANK create music that allows them to connect — with each other, with their family and friends, and eventually with their fans. Their sound reaches out to the people around them, echoing through their relationships and creating sincere links of companionship, support, and compassion.

The last episode of Glass Heart acts as a TENBLANK concert: its main purpose is to illustrate — visually and auditorily — how far these characters have come and how deeply it has bound them together. To punctuate that message, Akane’s mother, Momoko (YOU), is given a line that summarises the entire series:

Music is about discovering what’s happening inside you. You have to face yourself thoroughly, expose your whole self, and only then can you move someone’s heart.

As our four protagonists come together to create something bigger than any of them individually, they realise that music is a unique tool for self-expression and self-discovery, a means of bringing people together, and a conduit for emotion. That’s what these characters are chasing. That’s what ties us to their story. That’s what Glass Heart is truly about — everything else is just narrative fluff.

A Passion Project: A Committed Cast & Crew

Glass Heart finds its identity in its profound emotional depth, its astonishing score and soundtrack, and its superb artistic direction. Music and visuals are so tightly intertwined that it is impossible to separate them. While the visual effects are a bit grating at times, Kakimoto and Goto offer a mesmerising piece of work: their compositions, lighting, and colours are simply gorgeous (and incredibly effective).

According to Netflix, the soundtrack was composed by 26 artists who made up “a diverse and stellar lineup of leading musicians from Japan’s current music scene,” including (my personal favourites) RADWIMPS’ Noda Yojiro, ONE OK ROCK’s Taka, [Alexandros]’s Kawakami Yohei, and Tanaka (Boku no Lyric no Bōyomi). If you’re familiar with their work, I’m sure you’ll spot their signature beats in the amazing album they put together for the series.

TENBLANK wouldn’t exist without the marvellous work of its performers either. Netflix also announced that “the actors dedicat[ed] over a year to learning instruments, singing, and even making their actual debut as a band” — and you can feel that dedication. The characters’ music-making process is conveyed through pure energy and passion that radiates constantly and naturally throughout. This is a series charged with emotion, melody, and appeal, and that’s also thanks to its vibrant — and perfectly delivered — musical sequences.

Satoh, who also produced the series, clearly gave his heart and soul to Naoki — his intonation, gaze, and intensity are unlike anything he’s ever done. While he’s a powerful lead, we need to highlight Shison’s irresistible charm as a second male lead. He’s absolutely spellbinding as Sakamoto, giving Satoh a run for his money. Following Light of My Lion, Miyazaki continues to show that she’s an unstoppable force of nature, and Machida offers an admirable mix of maturity, sensibility, and enthusiasm. All together, they develop this undeniable synergy and convey their characters’ complexities with prowess. A final shout-out needs to go to the one-and-only Suda Masaki, who (once again) moulds a complicated character through a profoundly nuanced performance.

Singing Off-Key: The Weakness of Glass Heart

Glass Heart is an electrifying, enchanting tale thanks to its devotion to music and its genuine theme. The show has an unmistakable thematic core which is fully developed and delivered. It’s this message that creates a bridge with the audience and allows us to become immersed in its universe. However, Glass Heart has an off-pitch element: the story doesn’t have a clear narrative objective; that is, its plot lacks structure and intent.

The script introduces a series of completely diverse and often random conflicts that fail to receive any proper resolution. Separate storylines are introduced, suddenly resolved, and disappear without relating to one another or leading to a common goal. Melodramatic exchanges exist for the sake of melodrama, and supporting characters exist only to facilitate these exchanges. Unfortunately, secondary roles — especially the foil and the antagonistic ones — are given awfully shallow characterisation and clichéd lines that don’t add anything of substance to the story. So, despite its mesmerising artistic direction, Glass Heart gets lost in a narrative composed of disjointed conflicts that quickly receive unnatural or miraculous solutions and seems to waste precious time with supporting characters that feel like irrelevant caricatures.

Should You Watch Glass Heart?

While Glass Heart isn’t perfect, it’s definitely a story that deserves to be told — and carefully listened to. “Glass hearts” might be the ones that Naoki believes to have broken throughout his career, but in this Netflix adaptation, it stands more for these fragile souls that become transparent through their music. As the members of TENBLANK use their music to discover who they are and express their innermost emotions to the world, they embrace their vulnerability, offering their own glass hearts to the people that surround them. Like glass, they eventually allow light to pass through. Like glass, they are strong yet brittle. In the end, aren’t we all a bit like that? That’s why their quest for more vulnerable, more sincere, and more self-aware selves resonates as loud as the music they play.

Thanks to its sublime, unforgettable musical sequences, talented and charismatic cast, and heartfelt dedication to its theme, Glass Heart succeeds despite its narrative flaws. If you love music and its power to connect us all, be sure that TENBLANK will guide you through a moving, captivating, and dynamic exploration of sound, heart, and self-expression.

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