"IRIS OUT": an anime theme is Japan's biggest song of 2026

Some songs get under your skin, and some also break an industry's accounting. Kenshi Yonezu's "IRIS OUT" did both. It is the main theme of Chainsaw Man – The Movie: Reze Arc, the MAPPA-animated adaptation of Tatsuki Fujimoto's manga, and at this point in 2026 it is, quite simply, the biggest song in Japan.

The run started on 15 September 2025 with the digital release; the physical edition followed on 24 September, as a double A-side single shared with Hikaru Utada's "Jane Doe", the film's ending theme. Two of the heaviest voices in contemporary Japanese pop on the same disc, pushed by an anime film. It already smelled like an event.

The numbers settled it. "IRIS OUT" hit number one on the Billboard Japan Hot 100 and topped Billboard Japan's 2026 mid-year chart. It was also number one on Oricon's combined singles ranking and spent eleven consecutive weeks atop Oricon's weekly streaming chart, something no male solo artist had done before. Abroad it peaked at number 5 on the Billboard Global 200 — the highest placement ever for a Japanese-language song on that chart.

What is interesting is not only the record but what it reveals. For years the anime theme was treated as a subgenre, a corridor running alongside pop. Today it is the main road: the opening of your favourite series competes — and wins — on the same table as everything else. And it is not a one-song phenomenon. Look at the credits of Re:Zero's fourth season, with Konomi Suzuki and Ashnikko on the opening produced by Giga and TeddyLoid, and MYTH & ROID with TK from Ling tosite sigure on the ending, to see the size of the chips now being pushed onto the table.

If you have never heard "IRIS OUT" outside the film, try it on headphones with no picture. That thing that sounds like noise at the start and then resolves into a chorus is exactly what Yonezu does best: making you believe you have lost your footing, then catching you right on time.