Mochiru: Asset Longevity Sim

Mochiru is a fully offline retirement asset longevity simulator covering your whole financial lifecycle: accumulation, retirement, and drawdown. It answers one question with Monte Carlo simulation: how long will your money last?

WHO PLANS WITH MOCHIRU

• You want to see, in numbers, how many years your retirement assets will last
• You are planning FIRE / early retirement and want distributions, not a single optimistic line
• You want a drawdown plan that includes your pension, on your own assumptions
• You want everything on-device: no account linking, no sign-up

WHAT THE SIMULATION SHOWS

• Visualize success rate, depletion probability, asset longevity, and terminal wealth as a fan chart
• Enter your public pension (claiming age 60-75) and other regular income; income is deducted from required withdrawals
• Switch between four withdrawal strategies: fixed amount, fixed rate, dynamic guardrail, floor and ceiling
• Inverse analysis: solve the withdrawal amount that meets a target success rate (80-95%)
• Sensitivity analysis: sweep withdrawal rate, retirement age, and equity ratio
• Actuals tracking: log your total assets and compare reality with the plan
• Share your result as a single image (free)
• 5-question quick start gets you to your first result in seconds
• Siri Shortcuts to check your success rate or rerun the simulation

PREMIUM (one-time purchase, no subscription)

• Sequence-of-returns risk analysis, currency-hedge comparison, historical backtest
• Unlimited scenario saving and side-by-side comparison, PDF report export, higher simulation path counts

WHY MOCHIRU

• Built for JPY-based investors holding USD equities: it preserves the crash correlation where falling stocks and a strengthening yen hit your assets at the same time - a risk that simple "expected return plus risk" tools often miss
• Parametric assumptions plus historical block-bootstrap sampling

PRIVACY

• All calculation, input, and records stay on your device. Zero data collection, no account linking, no sign-up. The app uses the network only to purchase, to restore a purchase, and to open the legal pages.

IN THIS VERSION

• Plan in euros or US dollars as well as yen. Your base currency also decides which way the exchange rate moves in a crash
• Choose the app's language separately from the device - 34 languages
• FIRE: solve for the earliest age you could retire on your current plan (free)
• Crisis scenarios: compare eight assumptions such as a 2008-style crash, a lost decade, or high inflation (Premium)
• New assumption presets: Conservative, Standard, Optimistic
• One-off income (inheritance, property sale, severance pay) and more one-time expense categories: home renovation, a car, supporting family, private medical care, moving, travel, a care home
• Public pensions can be index-linked and paid 12 or 14 times a year. Choosing Spain as your country switches the currency, the pension shape and the wording (taxes are still not modeled)
• Apple Watch app and complications keep your latest result on your wrist
• On iOS 26 devices an on-device model writes a short explanation of your result. Nothing is sent anywhere

NOTE

This app is a simulation for general information and learning purposes. It does not recommend specific financial products or advise on the timing of trades. Results are calculations based on the assumptions you enter and do not guarantee future investment performance. The series used in "Historical" mode is a bundled sample (synthetic data), not real market data.