timelesz's 'Kienai Hanabi': Theme of Love and Memories

A few days ago, timelesz announced their upcoming second single under the new eight-member lineup, “Kienai Hanabi.” At first glance, the release seemed to present the group’s softer side through an emotional summer pop ballad centered around fleeting memories and fireworks lingering against the night sky.

Two individuals pose together holding a decorative globe while standing in front of a colorful poster featuring anime characters. The male figure wears a light blue polo shirt, and the female figure dons a floral dress.

But with the newly revealed details surrounding Shori Sato’s upcoming anime film Kimi to Hanabi to Yakusoku to (“You, Fireworks, and the Promise”), the emotional core of the song suddenly feels much clearer.

“Kienai Hanabi” has now been confirmed as the film’s official theme song — written specifically for the movie itself — and the connection between the two works feels deeply intentional. Both the song and the film revolve around the same bittersweet idea: that some moments are painfully temporary, yet continue to live on within people long after they disappear.

「ねぇ、運命って信じる？」

　＼＼　　　　　　　　　／／

　　映画『君と花火と約束と』
　　　　　本予告解禁

　／／　　　　　　　　＼＼

　主題歌 / timelesz [ 消えない花火 ]

映画きみはな
2026年7月17日(金)公開✨
佐藤勝利(timelesz) 原菜乃華高橋李依 pic.twitter.com/JaZA2gKTy4
— 映画『君と花火と約束と』公式 (@kimi_hana_movie) May 18, 2026

Set against the backdrop of the famous Nagaoka Fireworks Festival in Niigata, the film tells a time-crossing love story connected by a single painting of fireworks. Likewise, “Kienai Hanabi” uses fireworks not simply as a visual motif, but as an emotional metaphor for encounters, memories, and feelings that burn brightly for only a brief moment before fading from sight.

There is something particularly emotional about that imagery within Japanese summer culture itself. Fireworks festivals are often tied to youth, nostalgia, confessions, reunions, and endings — moments people already know cannot last forever even while they are living through them. Thus, the title “Kienai Hanabi” (消えない花火; roughly “Fireworks That Never Fade”) almost feels contradictory by design. Fireworks are meant to disappear. What remains instead are the emotions attached to them.

That emotional contradiction appears to sit at the heart of both the film and the song. Rather than focusing on dramatic heartbreak, “Kienai Hanabi” seems more interested in the quiet ache left behind by meaningful moments — the kind of memories that continue glowing softly somewhere deep inside long after summer has ended.

Shori himself reflected on that exact feeling in his comment regarding the theme song. While admitting he felt pressure because of how wonderful he found the film itself, he shared that he ultimately felt he had “encountered” the song in the same way the film’s characters encounter one another. He described fireworks as “a momentary sparkle,” but also something whose emotions remain forever deep within the heart.

It is a simple observation, yet one that perfectly captures why both the song and the film feel emotionally resonant. Neither is really about fireworks themselves, but about the traces people leave behind in each other long after a single moment has passed.

Shori Sato Comment

We are honored that timelesz’s ‘Kienai Hanabi’ has been chosen as the theme song for the film Kimi to Hanabi to Yakusoku to.

The film itself is truly wonderful, so naturally I felt a sense of pressure as well…
But just as Makoto and Hikaru were able to meet each other, I feel like I was able to encounter this song too.

Because of that, I can confidently share it with everyone.

Fireworks may only shine for a brief moment.
But the feelings they leave behind can remain forever deep within the heart.

I think we were able to create a theme song that carries that kind of emotion.

I truly hope it reaches you.