About those so called 'leeches'

I’ve heard quite a couple of mentions of them but I still haven’t caught on to what they are exactly… Could anyone give an explanation on what they are?

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From what I’ve gathered, a leech is a review that just won’t stick in your memory and can end up wasting your time learning it over and over. Some people like to isolate their leeches so they can focus on them seperately and individually.


This article explains leeches pretty well. It was written for Chinese learners, but the concept is the same.

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Basically, in the context of WaniKani, leeches are radicals, kanji, or vocab that just won’t stick in your memory through the usual SRS intervals no matter how long you try. Usually they have to be squashed through practicing them outside of WaniKani, either though Anki, userscripts, or some other method.


People usually practice them using the self study sceipt. It has an option on there to just learn leeches.

You could also use Anki or Kitsun.

For a list of leeches with a bunch of specific details, have a look at this:


Everyone has posted a lot of great advice and instructions!

It could be helpful if you see an example of what my leeches are:
交じる・混じる 「まじる」 - to be mixed, intransitive
交わる 「まじわる」 - to intersect, intransitive
交ぜる・混ぜる 「まぜる」 - to mix, transitive (this one is burned but just to illustrate a point I’ll list it)

These words are my oldest leeches because they start with the same kanji and the same first syllable “ma”, sometimes the same second syllable “ji”, and all end with the same syllable “ru”. Sometime the kanji contains only one syllable, “ma” and sometimes it contains two “ma+ji”. There’s three of them that all look different and sound different. They feel like a total mess to me and my brain hasn’t recognized a pattern with their forms.

I also haven’t encountered them enough in my other studies to stick the correct readings and definitions, and the worst part is that they usually aren’t used in cooking recipes because the alternate kanji 混 is typically used. I think I managed to burn 交ぜる・混ぜる because I’ve seen it the most in recipes.

I think I also learned them too close together, when I probably should have only learned one at a time and given myself like a week or two between the different forms.

Sometimes I can remember them and level them up to guru or master, but most of the time I get mixed up and they go back to apprentice. Because it’s been like 8 months since I learned them, and I still haven’t burned them by this point (but I’ve burned almost every other word in their levels), they’re leeches.


Classic leeches. Because you see them in a big stack of other things, it’s easy to get wrong, remember long enough to get the re-question right, then immediately forget again what makes it different from the other two. I think contrary to the “too close together” theory, it was just with too many other competing things.

Best thing to do with those is take just those 3 things, and drill them together until you kill it. Make it so you can never mix those up again. Obviously, you can’t put that much effort on everything (or if you could, it would be a waste); that’s why you wait until the SRS shows you you need to.

Speaking of, 悪気 just bit me again. I’m going to have to make TWO flash cards, one for 悪気 and one for 意地悪 and do just those two a hundred times until I know which is which reflexively.

How do you see what your leeches are?

This way is kinda only convenient if you have burned items:

Look through your radical, kanji, and vocabulary levels. For example, look at the Pleasant list for vocabulary. These are some of the first words you’ve ever studied. Let’s say you’ve burned most of level 1 (blacked out words). Any words that aren’t blacked out means you haven’t burned them yet, even though the rest in that list already have been. Those are leeches, they should have been burned a long time ago like the rest of those words.

If you don’t have a lot of burns in any levels yet, then it’ll be harder to clearly tell. You could click each word and see what level it is, and figure out the average. If your level 1 words are mostly in the same group (mostly all guru/master/enlightened), but there’s a few that are a level or two lower, those are leeches too.

You could also keep a note file/write down any words during your reviews that you know for a fact give you trouble, or you know you learned a long time ago.

There’s also apps and userscripts in the forums you can use which will help you figure out what words are leeches. Some apps do it automatically, and some apps let you decide how old or underleveled a word needs to be for it to be considered a leech.

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I use this leech trainer

it shows up like this on my dashboard, and you can customize what counts as a leech. I haven’t done any customization to it but its really helpful. I also use the Self-Study Script as well.

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