Tsubomi - Fertility & Cycle

Log basal body temperature and symptoms in one minute. Tsubomi predicts your ovulation and period windows with gentle reminders. All data stays on your device.

Tsubomi is a gentle fertility & menstrual cycle journal for women who want to know their body better.

Record your basal body temperature each morning, and Tsubomi automatically detects your cycle phase — menstrual, follicular, ovulation, or luteal. Ovulation and next-period predictions are shown quietly, without pressure.

――― ● A minute a morning, a lifetime of understanding ― Enter BBT from 36.00 to 38.00°C in 0.05°C steps ― Log mood and symptoms with emoji and chips ― One page a day, one minute to complete

● Your cycle, beautifully visualized ― BBT line chart across your last two cycles ― Phase coloring: menstrual, follicular, fertile, luteal ― Average cycle length and variability at a glance

● Reminders that don't push ― Gentle nudge the day before predicted ovulation ― Soft heads-up three days before your period ― Never aggressive, never guilt-inducing

● Privacy by design ― All data stored only on your device ― No cloud, no server, no third parties

――― 【Tsubomi Pro】 ・Unlimited cycle history ・Cycle and BBT pattern insights ・CSV export for your records

Monthly: ¥480 (eligible customers may receive a 7-day free trial) Yearly: ¥4,800 (eligible customers may receive a 7-day free trial, about ¥400/mo)

The purchase sheet shows eligibility and current pricing. Subscriptions renew automatically. Manage or cancel in Apple Account settings at least 24 hours before renewal.

Optional consumable tips are available separately to support development.

Privacy: https://starcrown.co.jp/privacy Terms: https://starcrown.co.jp/terms

――― Note: Tsubomi is not a medical device and does not provide medical advice. For questions about pregnancy, fertility treatments, or reproductive health, please consult your healthcare provider.

Made by Starcrown, Inc.