Walk into any gift shop in Nagasaki and you’ll see the same elegant yellow boxes stacked to the ceiling: castella — kasutera in Japanese — a golden sponge cake with a dark caramelised top and a whisper of honey. It is one of Japan’s most loved sweets, the default omiyage gift from Nagasaki, and the taste of childhood for millions of Japanese people.
And its name is Portuguese.
Castella comes from pão de Castela — “bread of Castile” — the name Portuguese merchants and missionaries used for the European sponge-style cakes they carried to Japan in the late 1500s, during the Nanban trade period. Like tempura, it landed in Nagasaki, the port Portugal opened in 1571. Unlike tempura, it barely had to change to conquer the country.
Why a Cake Survived When the Portuguese Didn’t
The Portuguese were expelled from Japan in 1639, when the country closed itself off for over two centuries. Most European things vanished with them. Castella didn’t — for one beautifully practical reason: it keeps.
Made from just eggs, sugar, flour and mizuame (a Japanese starch syrup adopted into the recipe), castella has no butter and no dairy — rare things in pre-modern Japan anyway — and it stays moist for days. In an era without refrigeration, a rich, long-lasting sweet was treasure. Nagasaki’s bakers kept making it, refined it with Japanese ingredients and Japanese precision, and turned a foreign visitor into a local institution.
The oldest castella houses are still trading. Fukusaya, founded in Nagasaki in 1624 — while Portuguese ships were still arriving — bakes it to this day. Walk past their shop and you’re looking at a business older than the sakoku isolation itself.
How Castella Differs From Its Portuguese Parents
If you’ve eaten Portuguese pão de ló, castella will feel like meeting a cousin: familiar face, different accent.
- Texture: pão de ló is airy, sometimes deliberately underbaked and custardy in the middle (the famous Ovar style). Castella is dense, fine-crumbed, bouncy — almost like a sweet, springy bread.
- Sweetener: castella uses mizuame syrup and often honey, which give it that signature moistness and sheen.
- The bottom: traditional Nagasaki castella hides coarse zarame sugar crystals at its base — a gentle crunch Portuguese cakes never had.
- The shape: baked in long wooden frames and sold in neat rectangular blocks, sliced with geometric precision. Very Japan.
It is, in miniature, the same story as tempura: Portugal supplied the idea, Japan supplied the perfectionism.
Where to Try It (Without Flying to Nagasaki)
In the UK, castella turns up in Japanese bakeries and larger Japanese food shops, usually in individually wrapped slices. Japan Centre in London regularly stocks it, and Taiwanese-style castella (a jigglier, souffléd descendant) has been popping up in Chinatowns across the country. For the real Nagasaki article, look for the words kasutera or “honey castella” and check the ingredient list is short — eggs, flour, sugar, syrup, honey. That’s it.
📚 Bake the Portugal–Japan story at home
[Replace with AAWP box — a Japanese baking book that includes kasutera, or a castella baking frame/tin for making it at home.]
Affiliate link — I earn a small commission at no extra cost to you.
Or bake it. Castella is one of the most satisfying cakes a home baker can attempt — few ingredients, all technique — and I’ll be publishing my own recipe with UK measures soon, alongside its Portuguese cousin pão de ló so you can taste them side by side.
One Cake, Two Homes
Here’s what I love most about castella. In Portugal, almost nobody knows Japan took our cake. In Japan, almost everybody knows the cake came from Portugal — it’s printed on the boxes, taught in schools, celebrated in Nagasaki’s festivals. One side forgot; the other remembered for 400 years.
Momo Ikigai exists partly to fix that imbalance — to tell the Portuguese side of a story the Japanese never stopped telling. If you’re new here, start here, or go deeper with how Portugal gave Japan tempura.