This past weekend saw me immersed in the planning and execution of a large-scale event. Consequently, the weekend newsletter went unsent for the first time in nearly a year to the day. Omataseshimashita (お待たせしました), as the familiar phrase goes—thank you for waiting.
There may be something inherent to this time of year that invites a lapse. In London, May brings longer light, warmer streets, and a subtle uptick in restlessness—the sense that something is about to begin, even if no one has said as much. Activity seems to hum all around: the calendar fills with plans, the weather encourages drift, and the city becomes reluctant to stay indoors.
Or perhaps it was simply a matter of time and energy overtaking me, as I attended to the particulars that a significant gathering of people demands. From among those details, a tidbit offers itself up as this week’s subject. If you're a new reader and this is your first Tokyothèque, you might consider perusing some of the sixty-plus previous editions to acquaint yourself better with the newsletter's usual rhythm and scope.
The detail in question was the acquisition of a taru (樽) cask and eighteen litres of nihonshu (日本酒), Japanese sake (酒), to fill it. In Japan, an event organiser might source a pre-filled barrel of aged taruzake, the wood infusing its flavour. But in London, such an indulgence is rare and costly. The more practical solution favoured by the city's Japanese businesses and communities is the rent-and-fill method—a workaround I, too, adopted.
But why go to such lengths? Wouldn't bottle service have sufficed? As it transpires, the effort wasn't a mere logistical flex—it was ceremonial. The event featured a kagamibiraki (鏡開き), a time-honoured ritual in which a sake barrel is opened in dramatic fashion to mark an auspicious beginning. At the centre of this gesture stood the komodaru (菰樽), a visually ellaborate taru bound in straw, often adorned with a brewery crest or celebratory emblem. In such moments, neither bottles nor an ordinary barrel will do.
The lid, known by sake producers as the kagami-ita (鏡板)—literally "mirror board"—is a smooth, circular wooden disc that calls to mind the polished surface of a bronze mirror. This imagery underpins the use of kagami (鏡), meaning mirror, in the ritual's name. The second element, hiraki (開き), meaning "opening," becomes biraki through rendaku—a phonological shift in Japanese where unvoiced consonants are softened when combined. Together, the term kagamibiraki translates directly to "mirror opening."
One must also assemble a set of implements, each with a specific purpose, to enact the ritual. To break open the lid, principal attendees take up a kizuchi (木槌), a hefty wooden mallet, and strike, splitting it cleanly in two. The mallet is often adorned with kōhaku (紅白) ribbon, the pairing of red and white being a familiar emblem of celebration in Japan. In Shintō aesthetics, red embodies vitality and protection, while white signifies purity and new beginnings.
Likewise, in Shintō cosmology, the mirror is an emblem of clarity, truth, and revelation. This is why the kagami-ita is not to be broken but to be opened. The distinction matters—kowasu (壊す), meaning "to break," carries the weight of destruction. By contrast, hiraki connotes an opening—an act of unveiling, of allowing something to emerge. It is a subtle linguistic shift that lends a sense of reverence and restraint to the otherwise forceful image of hammering down on a cask of alcohol.
Even so, the strike is delivered with clear intent, ushered in by a spirited, synchronised call of yoisho (よいしょ), a wordless exclamation that gives voice to collective effort. In this context, it binds the group in a moment of shared purpose, signalling the transition from preparation to celebration. It was my first time participating in kagamibiraki, and the moment we struck, I sensed the atmosphere shift. Instant matsuri (祭り) cheer set in, the kind usually reserved for Japan's summer festivals. The ritual's purpose of opening good fortune charged the air.
Our London rendition deviated slightly from tradition. As the ceremonial cask is rented and shared among various groups, the kagami-ita arrives pre-split, though precisely enough rejoined that the seam is discrete. When booking the komodaru, there was a murmur of doubt over whether the pre-split lid departs too far from custom. Yet the prevailing sentiment of the group aligned with a Shintō sensibility: that sincerity of intention outweighs exact adherence to form. And when separated by some 9,580 miles from Japan, it felt wiser to honour the spirit than abandon the gesture in the face of such complications.
Once the lid is opened, the sake is ladled and served in masu (枡)—square wooden cups once used to measure rice. Each masu was ordered directly from Japan for this occasion: one per guest, engraved with the event's details, and intended as a keepsake. The masu is a modest vessel crafted from hinoki cypress. It is light, fragrant, and water-resistant—so lightweight that a guest travelling from Tokyo was able to bring the entire set as checked luggage.
Even so, the masu elevates a simple sip of sake into something more. The hinoki's scent mingles with the drink's aroma, evoking onsen baths, the hush of shrine corridors, and the clean cut of freshly planed timber—sensations of Japan imported straight to London. In the absence of true taruzake, that infusion of wood becomes all the more vital. It emphasises sake's warming characteristics and complements the shared pouring of the cask; an invitation to drink in unison and embody a collective wish for harmony and prosperity.
In the modern era, the ritual has found a firm place in corporate culture. It is commonly performed at company inaugurations or milestone anniversaries—ceremonies that honour the passing of time while setting intentions for what lies ahead. Executives and employees assemble to strike the lid, a gesture of collective purpose and resolve. It is both celebratory and earnest: revelry imbued with the weight of commitment. The spirited clatter of the wooden mallet, set against the deliberate choreography, speaks to this equilibrium.
Kagamibiraki is also performed at weddings, where it symbolises the beginning of a new chapter and a wish for enduring harmony between the couple and their families. Similarly, it appears at the commencement of major construction projects, sporting events, and cultural festivals.
The practice's origins are often traced to the early Edo period (1603–1868), when legend holds that Tokugawa Ietsuna, the fourth shōgun, broke open a sake barrel with his retainers on the eve of a pivotal battle in a symbolic act intended as a prayer for victory. As the story goes, they prevailed, and the gesture assumed auspicious overtones, gradually evolving into a custom for marking new beginnings.
Judging by how I felt on Sunday after opening the mirror on Saturday, I'd wager that Ietsuna's men did not drain the entire cask—that would not have left them battle-ready. Either way, I found no verifiable historical record to confirm this oft-repeated tale. The narrative appears more modern myth than fact, perhaps circulated by sake brewers or event organisers eager to cloak the ritual in historical weight. Still, it feels apt—an origin story well suited to a tradition that traffics in both high spirits and the spiritual.
Some question whether the sake-centred ritual should bear the name kagamibiraki at all. Originally, and more traditionally, the term refers to a New Year's custom in which mirror-shaped rice cakes—kagami mochi (鏡餅)—are broken and consumed as offerings to the gods. The adaptation to sake barrels seems to be the more recent innovation.
While kagamibiraki is most strongly rooted in sake-producing regions like Kyoto, particularly the Fushimi district, Tokyo, with its flair for urban pageantry, seldom sits out the writing of cultural history. The city gave rise to the ritual's contemporary, media-savvy form during the postwar economic boom. Hotel banquets, department store openings, and televised New Year's broadcasts shaped the version now recognised across Japan.
And so, we find ourselves full circle in Tokyo. The mirror has been opened, and starting tomorrow morning, I set off on over a month of fresh travel, beginning in Europe and eventually returning to Japan, to its capital, the city I hold dearest. My mind brims: deep-dive newsletters, walking routes, videos, photo sets, and travelogues. I'll share many of them with you live as I trace my route from place to place in the weeks ahead. But for now, my suitcase—empty, open, and expectant—calls to be packed.
Until we meet in transit,
AJ