A memory layer for every language you carry.

The problem we are fixing

Finding a word has never been easier. ChatGPT explains it, Duolingo surfaces it, a screenshot captures it. The hard part is keeping it. Words scatter across apps and notes and threads, and a week later they are gone. Koboshi gives those words one home and a memory system that brings them back until they are yours for good.

Where the name comes from

Koboshi comes from okiagari-koboshi (起き上がり小法師), the Japanese doll that always rights itself when it is knocked over. Nana korobi ya oki — fall seven times, stand up eight. Forgetting a word is not failure. It is part of remembering. The whole app is built around that idea: you are not punished for forgetting, you are simply brought back to the word at the right moment.

The polyglot idea at the core

Most apps assume one native language and one target. Real multilingual people do not work that way. Koboshi treats meaning as language-independent: look a word up once and see it across every language you know, with the nuance that one language alone often cannot capture. Learning one language ends up strengthening the others — and the cross-language links you confirm as you study are what make the whole thing smarter over time.

Who it is for

Heritage speakers filling in the words they never formally learned. Polyglots juggling several languages at once. Intermediate learners stuck at the B1–B2 wall who need vocabulary that recalls fast enough to follow real speech. If you already use ChatGPT, Duolingo, YouTube or a tutor, Koboshi is the memory layer that sits underneath them all.