Rokuyo Calendar: Taian to Butsumetsu

Rokuyo is one of the simplest timing systems in Sidera’s experimental Planner New, and that is why it is useful. It does not ask you to read a birth chart. It does not ask you to compare transits. It gives each date one of six Japanese calendar labels, then lets you decide whether that cultural timing marker matters for your plan.

The labels are familiar in Japan: Taian, Shakku, Sensho, Tomobiki, Sakimake, and Butsumetsu. They often appear in fine print on calendars and can influence weddings, funerals, openings, and ceremonial choices. In Planner New, Rokuyo becomes a readable month view with a selected-day explanation and top-days list.

The screenshots in this article are real captures from Sidera Planner New, taken on June 27, 2026 from a repeatable June 2026 test profile – not stock mockups or composites. The Rokuyo layer you see runs entirely in the browser: it converts each Gregorian date to its lunar month and day using a client-side lunar calendar library, then applies the standard six-day modular rule to assign the label. What you see in the UI is the same calculation any user would get when opening their own Planner New calendar.

What Rokuyo Is

Rokuyo means “six days.” It is a repeating six-label calendar system used as a fortune or timing marker in Japan. Modern Japanese life does not follow it uniformly, but the labels still show up in cultural timing decisions.

The six labels are:

The mistake is to overcomplicate Rokuyo. It is not a full electional astrology system. It is a compact cultural calendar signal.

For a public overview of Rokuyo’s role in Japan, Go! Go! Nihon’s Rokuyo explainer gives a useful modern introduction.

How Sidera Shows Rokuyo

Sidera’s Planner New Rokuyo tab has the same structure as the other systems: calendar, selected day, top days, and day log.

The selected day panel shows:

• score
• Rokuyo label
• signal phrase
• lunar date
• modular rule
• conversion source
• method confidence

In the screenshot report, June 27, 2026 is labeled Taian with a 9.2 score and 90% method confidence. That is a strong Rokuyo signal. It does not mean the day is universally perfect. It means the Rokuyo layer classifies the date as highly favorable according to its method.

Why Lunar Conversion Matters

The Rokuyo calculation may look simple, but it depends on the lunar date. In the current Planner New implementation, Sidera converts the Gregorian date to a lunar month/day, then applies the modular rule:

(lunarMonth + lunarDay) % 6

That maps the day to one of the six labels.

This is why the difficult part is not the six-day cycle itself. The difficult part is reproducible lunar conversion. If the lunar month/day is wrong, the Rokuyo label can be wrong.

That is also why Sidera displays method confidence. A high confidence value means the system had enough conversion coverage to render the result. It does not mean the day is guaranteed lucky.

Taian Meaning

Taian is generally treated as the most auspicious Rokuyo label. People may prefer it for weddings, openings, ceremonies, or important beginnings.

In a planning app, Taian is best understood as a green-light cultural marker:

• good for visible beginnings
• good for public commitments
• good for ceremonies when Rokuyo matters to the people involved
• useful as a secondary confirmation when other timing systems also look clean

Taian should not override reality. A Taian date with an unready contract, unavailable guests, weak launch plan, or emotional pressure is still not a good date.

The smarter question is: “If the real-world plan is ready, does Taian add cultural timing support?”

A second practical use: if two candidate dates look comparable across your other timing checks, Taian versus a neutral label can serve as a clean tiebreaker. You are not claiming Rokuyo is more accurate than transit analysis. You are using a second independent layer with a different cultural logic behind it to add directional weight. When two systems agree, the signal is stronger than when one system leans positive and you are searching for confirmation in the other.

Butsumetsu Meaning

Butsumetsu is commonly treated as the least auspicious Rokuyo label. Many people avoid it for weddings and other celebratory events. That avoidance is cultural, not universal law.

In modern use, Butsumetsu can also be read more psychologically:

• not ideal for celebratory beginnings
• potentially useful for endings or clearing
• a day to avoid forcing public optimism
• a reminder to check whether the action is symbolic or practical

That nuance matters. A label that is poor for a wedding may not be useless for cleanup, cancellation, closure, or reflection.

The Half-Day Labels

Not every Rokuyo label works like Taian or Butsumetsu.

Some labels carry time-of-day nuance:

• Sensho can be read as better earlier.
• Sakimake can be read as better later.
• Shakku is often treated as difficult except for a midday window in some interpretations.
• Tomobiki carries a social tone and is famously avoided for funerals in many contexts.

Planner New is currently a day-level display. It can show the label and signal, but it does not yet turn every half-day nuance into a precise local hour recommendation.

That is fine for an experimental layer. The UI should help users understand the label first. Precision can come later.

Reading the Top Days View

The top-days view turns Rokuyo into a practical shortlist.

In the screenshot report, the top Rokuyo days for June 2026 include:

• Fri, Jun 5: Best all-day window - 9.2
• Mon, Jun 1: Move early - 7.0
• Tue, Jun 2: Socially supportive - 6.6

This is useful because users rarely need to debate every day. They need candidate dates. The top-days view turns the six labels into a planning list.

Using the Day Log With Rokuyo

The day log is where Rokuyo shifts from reference to personal data. After each notable day, users can record what happened: energy level, productivity, mood, outcome, or a short note on how the day felt.

Over a full lunar cycle, patterns can surface. You might notice that your Taian days consistently feel expansive, or that Sensho mornings are your most focused window. You might find Butsumetsu afternoons better for solo review than for client calls or external commitments.

None of this is the calendar instructing you. It is you observing whether the cultural timing signal correlates with your actual experience. That is the honest value of logging alongside an almanac layer.

In Planner New, the day log appears below the selected-day panel. Recording notes consistently across even one month gives you enough data to judge whether Rokuyo is a personally useful signal or just background color for your planning. If a pattern appears, you have learned something real about your own rhythms. If no pattern appears, you have useful data for that conclusion too.

When Rokuyo Is Useful

Rokuyo is useful when the people involved care about Japanese calendar timing or when you want a lightweight almanac layer beside other systems.

Use it for:

• wedding date awareness
• ceremony planning
• opening days
• personal milestones
• cultural context checks
• comparing candidate days when other timing systems are tied

Do not use it as the only factor for:

• legal timing
• medical timing
• financial decisions
• religious obligations
• anything where local custom, family expectations, or professional guidance should lead

How Rokuyo Compares With Western and Vedic Timing

Rokuyo is not trying to answer the same question as Western electional astrology or Vedic Muhurta.

Western timing asks about planetary conditions and the event chart. Vedic timing asks whether the moment fits Jyotish rules for beginning. Rokuyo gives a six-label cultural calendar signal.

That makes it a useful secondary filter.

Example:

• Western timing is supportive.
• Muhurta is mixed but usable.
• Rokuyo is Taian.
• The practical date works for everyone.

That is a stronger candidate than a day where only one system looks good and the real-world constraints are messy.

For broader date selection, compare this with what electional astrology is and best wedding date astrology ideas if the action is relational.

What Sidera Should Add Next

The current Rokuyo layer is a strong start because it is simple, explainable, and visually clear. The next improvements could be:

• half-day nuance in the selected-day panel
• clearer cultural caveats for weddings and funerals
• source labels for lunar conversion
• comparison warnings when other systems disagree
• user day logs grouped by Rokuyo label

If a user logs high energy or fulfillment on certain labels, the app could eventually show personal Rokuyo patterning without claiming universal truth.

The Practical Takeaway

Rokuyo is a six-day Japanese calendar signal. Taian is generally favorable. Butsumetsu is generally cautious. The other labels add time-of-day and social nuance.

Sidera’s Planner New makes Rokuyo useful by showing the label on a calendar, explaining the selected day, ranking top days, and displaying method confidence. Use it as a lightweight cultural timing layer, especially when choosing between dates that are already practical.

The best use is not “Rokuyo said yes, so I must.” It is “This day is practically ready, and Rokuyo adds one more supportive signal.”