When to use it?

My message card is a thin tool for a note you want delivered now and gone soon: share a QR and password; they read under a finger for one hour in the opening browser.

Thanks you do not want stuck in chat

Chat keeps polite or awkward thank-yous forever. Send a QR and the password separately. Use it for words that need to arrive once—not for notes meant to be revisited.

Birthday or anniversary surprises (QR first, password on the day)

Create early, share the QR, give the password on the day. Print the QR into wrapping or send the image. Handing over the password too early spoils the surprise.

Confessions or lines you do not want reread

Chat logs invite rereading and one-tap screenshots. Here, text does not appear until a finger is held. Add copy-block, first-browser binding, and a one-hour window: not perfect secrecy, but clearly harder to keep than a permanent chat log.

A short letter feel (vertical Japanese)

On the Japanese UI you can choose vertical writing—title, body, signature like a paper card. Meant for short notes, not long reports.

Shares you want on one device / browser only

Reading binds to the first unlocking browser. Useful when you want them to open once on their phone—not on a café PC or a shared tablet.

Hand-off when you do not share a messenger

No extra app—just a browser. Send the QR image or copy the URL. If you can say it face to face, you do not need a card.

What it is not

Not permanent letters, attachments, multi-device archives, or account history. Finger-reveal makes screenshots harder; it does not ban the OS capture button. A simple filter: out of chat history, enough to read once under a finger, and one browser enough?