Can Extreme Pop music be recreated on the Piano? Chainsaw Man Movie “Reze Arc” OST: IRIS OUT and Ru’s Piano Arrangement

If you’re a fan of Japanese anime, you can’t ignore Chainsaw Man. Chainsaw Man is a work by Tatsuki Fujimoto that has been serialized in Japan’s Weekly Shonen Jump since 2019 and continues to this day. The early plot of Chainsaw Man follows the protagonist Denji, who accidentally gains a unique transformation ability and becomes a devil hunter, facing unknown devils and experiencing chaos. Chainsaw Man is known for its unique world that portrays violent yet deeply human emotions, gaining popularity not just in Japan but worldwide. Denji lives on the boundary between humans and devils, dreams of ordinary happiness, but is constantly confronted by a brutal reality.

The theatrical release in Japan this September, Chainsaw Man: Reze Arc, continues the story from the TV series, focusing on Denji’s encounter with the mysterious girl Reze and the love and conflict that follow. With flashy action, the film also delicately portrays the instability of relationships and emotional wounds.

Today, we will take a look at the main OST of Chainsaw Man, IRIS OUT: pre-released theme song, which was sung by Kenshi Yonezu, who also worked on previous Chainsaw Man OSTs.

IRIS OUT is a fast-tempo pop song featuring a captivating ensemble of flashy rhythm bass, drums, piano runs, and synthesizer layers. The title “Iris Out” refers to the phenomenon of the pupils dilating. True to its name, the song’s relatively short length of around 2 minutes and 30 seconds leaves a strong impression while perfectly matching the film’s atmosphere.

<IRIS OUT : OST from Chainsaw Man Movie>

Structure of IRIS OUT

The structure of IRIS OUT is below:

 Intro – Verse 1 – Pre-Chorus – Chorus 1 – Bridge –

Verse 2 – Pre-Chorus 2 – Chorus 2 – Outro.

Similar to typical pop song structures, it manages to fit all sections efficiently into a short piece. Let’s look at each part in more detail.

• Intro: The synthesizer riff and bass immediately set the mood, followed by piano tremolos that build anticipation. The sweeping intro draws listeners into the song.

• Verse: The vocals begin, gradually increasing engagement, and tension is built through repetition, guiding the listener along the emotional line.

• Pre-Chorus: Sung quickly like a rap, maintaining the pace while calming the listener with the lyrics “IRIS OUT” before the explosive chorus.

• Chorus: The song’s most explosive and memorable section, highlighting emotional turmoil and themes of love plus obsession.

• Bridge: Enhances listener engagement with rhythmic and piano runs, supporting the emotional flow.

• Outro: Features continuous piano solo lines, maintaining a strong and fast-paced atmosphere, holding onto the emotions expressed throughout the piece.

Ru’s Piano Version: Faithful to the Original

How does Ru’s piano arrangement translate this to piano? The pop elements create an incredible synergy when arranged for piano. The wide range and powerful low end of the piano can carry much of a pop song’s energy. Ru’s version stays quite faithful to the original: the tempo is marked ♩ = 134, preserving the original tempo and rhythm, while the piano solo carefully reproduces vocal rhythms and synth textures.

<Ru’s piano: IRIS OUT piano ver.>

Piano Sounds Emulating Instruments

In the intro, Ru mimics the bass using the left hand’s lower register while reproducing the repeated 8th-note rhythm to match the song’s fast tempo. The right hand plays the synthesizer melody.

In the verse, piano key strikes mimic speech-like rapid runs, representing the original rap part. The interplay between left-hand rhythm and right-hand repetition creates a tense yet mesmerizing feeling, almost like expressing Denji’s anxious heartbeat through two hands.

In the pre-chorus, the left-hand bass deepens, increasing tension. Dynamics gradually grow, short notes extend, and patterns expand. By the chorus, the arrangement produces an explosive sound; crossed octaves and strong syncopation replace the original electronic drums and guitar, demonstrating Ru’s effort to convey the full band energy on a single piano.

The second verse’s pre-chorus becomes even more complex. The right hand moves across a wide range to depict the sparkling synth sounds from the original. The resulting echoes mimic electronic timbres.

Piano Technique at Its Peak

In the final chorus and outro, technique reaches its climax. The right hand plays melody and synth riffs simultaneously while the left hand drives rhythm like a drum loop. This requires high hand independence and practice but lets the performer feel the original track’s thrill. The last few measures fade, ending with the “iris out” effect—a lingering impression as if the screen slowly darkens.

Conclusion

Ru’s piano arrangement translates the original’s fast rhythms and electronic textures into piano while demonstrating expression beyond the instrument’s physical limits. Repeated patterns, octave rhythms, and echoed bass preserve the original’s tension and energy.

This arrangement faithfully follows the emotional structure of the original while adding new depth with the piano’s unique timbre. Looking for a challenging, faithful version of IRIS OUT rather than an easy simplified sheet? Please check out the score here!