Chutoro
中トロ

What is Chutoro?

Chutoro (中トロ, "medium fatty tuna") comes from the upper belly and back-adjacent areas of the Bluefin — a transitional zone where fat and lean muscle interleave in roughly equal measure. It is neither the direct intensity of Akami nor the melting richness of Otoro: it is the point where the two converge.

On a fish of the quality produced by Hosei Suisan, Chutoro is arguably the most interesting cut. The fat contributes silkiness and richness; the lean muscle beneath it carries umami that pure Otoro cannot achieve alone. This is why Chutoro is the cut we recommend to first-time buyers.

Sub-cuts of Chutoro

Chutoro is not a single uniform cut — it is a category that spans four distinct blocks of the fish, each with its own character. What you receive will depend on which block and sub-section is available that week. Understanding these differences explains why Chutoro from the belly can taste so different from Chutoro cut from the back.

Chiaigishi — the bloodline-adjacent sub-cut

Within both Harakami and Haranaka, the narrow band of meat running alongside the Chiai (bloodline) is called Chiaigishi. It is the darkest-colored section in the Chutoro zone and carries the most concentrated umami of any Chutoro sub-cut — while still maintaining the silky fat that defines the belly cuts. Moving away from the bloodline toward the outer belly, color transitions from deep red to near-white as fat content increases and the meat approaches Otoro in character, with fine marbling throughout. Harakami Chiaigishi is more intense than Haranaka Chiaigishi.

Hagashi — peeling from the sinew

In sections of Sekami where connective tissue is too dense to slice cleanly, we use the Hagashi technique: the layer of meat is carefully peeled away from the sinew network by hand rather than cut through it. The result is a piece entirely free of sinew — with a tenderness that rivals the belly cuts, but the stronger, more direct flavor characteristic of back meat. Hagashi is time-consuming work and the yield from each fish is small.

Wakaremi — the wrapped sub-cut of Senaka

Wakaremi sits at the dorsal fin edge of the Senaka block, enclosed within a band of strong sinew. Untrimmed, Wakaremi may be sold as Sujitoro — the sinew gives it a looser, pulled texture. Trimmed of its outer sinew layer, the interior is completely tender and carries a texture very similar to Hagashi Chutoro from Sekami: concentrated, fine-grained, with no resistance. When Wakaremi is offered by name at Sashimi DC, it has been properly trimmed.

How to eat it

8–10mm, Hira-zukuri, against the grain. Slice cold and allow 2–3 minutes on the plate before eating. As nigiri, the warmth of the rice gently melts the fat from below. Chutoro also takes well to light torching (Aburi) — a brief pass of a kitchen torch caramelizes the fat on the surface while leaving the interior raw.

Where this fish comes from

Every piece of Bluefin Tuna at Sashimi DC comes from Hosei Suisan (宝生水産), a farm in the Kamishima Wakamatsu area of the Goto Islands, Nagasaki Prefecture — the westernmost islands of Kyushu, where the Pacific and East China Sea converge.

The Goto Islands maintain water temperatures that never fall below 13°C in winter and rarely exceed 29°C in summer — the stable, narrow range that Bluefin Tuna require for consistent growth and quality. Hosei Suisan operates in the Kamishima Wakamatsu area, one of the most environmentally favored zones for marine aquaculture within the islands.

Hosei Suisan uses wild-caught seed stock (天然種苗) rather than hatchery-bred fish. Feed is sourced fresh and locally, centered on fresh mackerel (生サバ) bought directly by their own trucks from local fishermen. Director Tsuneya Yamashita explains the choice: mackerel produces better fat marbling and color than sardines. As mackerel catches have declined and prices risen in recent years, they secured dedicated year-round supply agreements with their fishing partners to maintain the standard. Post-harvest handling — the initial processing and preparation after the fish is landed — is also a focus: Ikejime is performed in Nagasaki, at source.

After Ikejime processing in Nagasaki, the fish is transported to a specialist Miyazaki processor where it is broken down into saku blocks, then flown Fukuoka → Haneda → IAD.