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The method and its sources

Last updated: 18 October 2026

Ōkini wasn't put together at random. Its principles come from what memory research knows best, and this page shows where they come from. It also says which parts are our own choices, because no study has tested Ōkini itself.

In short

Recalling the answer rather than choosing it

In Ōkini, you read a word or a sentence and type what it says, in full. There is never a list of answers to choose from. Recalling an answer yourself helps you remember it better than reading it again, and better than recognising it in a list: it is one of the most solid findings in memory research (Roediger and Karpicke, 2006; Rowland, 2014). The effect depends on one condition: seeing the right answer right after. Without a correction, answering from memory can even do worse than multiple choice (Kang et al., 2007). That's why Ōkini corrects you on every word and shows you the exact character that tripped you up.

Reviewing what you know less well, spaced out

Each series mixes new characters with the ones you still find hard. Reviewing something at spaced intervals, rather than all at once, strengthens long-term memory: a review of several hundred experiments confirms it (Cepeda et al., 2006). Correcting a mistake right away also helps you not to make it again (Pashler et al., 2005).

Characters that look alike, such as さ and ち or シ and ツ, are mixed on purpose in the recall questions. Comparing similar items helps tell them apart, and the more alike they are, the clearer the effect (Brunmair and Richter, 2019).

What comes along with it, and its limits

Every word and sentence in Ōkini comes from everyday life. As you keep running into them, many start to feel familiar without you learning them by heart. Research confirms that we learn words by meeting them, but it also shows that this is slow and depends on how many times we meet them (Uchihara et al., 2019; Waring and Takaki, 2003). That's why the same words come back often.

For grammar, research is even clearer: an explanation helps more than leaving patterns to sink in on their own (Norris and Ortega, 2000). So Ōkini doesn't rely on reading alone. A tip explains each new point the first time it appears, and the lessons notebook covers everything in detail.

What comes down to our choices

No mnemonics. The few studies on kana, with small groups, show no clear long-term advantage for mnemonic pictures (Matsunaga, 2003 and 2009). They help in other areas, but for kana we chose to let the characters sink in through reading.

No handwriting. Ōkini teaches you to read. To write on a phone, the keyboard offers you the characters and you only need to recognise them. Being able to draw characters from memory is useful, but it is a different skill, which can come later.

Real words from the very first step. No study has compared this approach with learning characters one at a time. It's a choice: reading right away what you'll want to read next, rather than reciting a chart.

No lives, points or countdowns. Studies on these game mechanics are mixed, and some find a small positive effect (Sailer and Homner, 2020). We'd rather you come back to read than to save a streak: it's a choice, not a scientific rule.

Two five-minute series a day. No study sets an ideal length. This pace is designed to fit into a busy day, and nothing stops you from doing more.

References

A question about the method, or a study we should read? Write to us at [email protected].