Hoshino-Invest

The problem. Personal finance is one of the most critical life skills, yet it is completely absent from school curricula. When kids only see abstract digital numbers without real-world context, it is incredibly difficult for them to grasp how money actually works—or how habits formed early impact their future.

Why I built it. I am passionate about personal finance and wanted a hands-on way to teach my daughter about money. Instead of building something in a silo and forcing it on her, we designed and built parts of the app together, treating her as the primary user to create an experience she actually enjoys using.

What it does. It is a progressive web app where my daughter tracks her income and expenses, “invests” her savings with us at a set interest rate, or borrows funds (incurring interest). A core feature is the monthly interest payout, which shows her exactly what she earned simply by saving. She can then choose to cash it out or reinvest it to experience compounding.

The benefits. Money concepts become highly visible and interactive. By watching her investments grow monthly, she learns the mechanics of compound interest firsthand. Collaborating on the project also showed her that great systems and software are built by listening to the user.

Features

• Income and expense ledger with a kid-friendly, collaboratively designed UI
• Monthly interest payout module with reinvestment/compounding triggers
• Family borrowing framework with transparent interest cost tracking
• Installable mobile PWA co-designed with the end-user (my daughter)
• Phased roadmap to introduce currency trading, interest rates, stocks, and ETFs