So when I first moved to Japan (for the second time), I went to an international party (kind of like a Japanese-Foreigner mixer… maybe I should write about those sometime). And at that party I met this girl named [I don’t remember]. She was one of the shortest Japanese people I’d ever met. Regular proportions and everything, but just really short. Actually, she was quite pretty.

Anyways, she was pretty cool, so we became friends, and we were talking on Line a few days later, and I was probably asking her a million questions about Japanese or Japan or talking about how I want to go swimming in the Arctic Ocean someday. I don’t really remember, and she told me I was 好奇心旺盛.

I think she said something like…

niko wa koukishin ousei da ne.

My first reaction was to [almost] vomit from kanji overload.

Then I looked up what would become one of my favorite Japanese words.


koukishin ousei
brimming with curiosity

(Definition from Weblio)

So, I if I were to translate what she said to me, I guess it would be something like:

You’re just brimming with curiosity.

Or maybe…

You’re such a curious person.

Anyways, I thought it was a cool phrase. And I asked my girlfriend Rei if people actually use in conversations, and she said yes, they do.

Speaking of Rei, she’s been writing about our adventures (currently in Thailand) on her blog, Rei Buffet. Actually, I shouldn’t call it a blog, because she calls it a 冒険記 (boukenki / adventure journal). If you want to challenge yourself with some fun Japanese, check it out! Plus, it’s about us… so that might be interesting for some people, too. My mom, for example. But… my mom can’t read Japanese. Anyways, if someone reads it, I’m sure Rei will be stoked.

Back to what I was saying…


好奇心 (koukishin) is the word for “curiosity” in Japanese.

If you look at the kanji, that makes total sense:

好 ([to] like) + 奇 (strange) + 心 (heart)


“a heart fond of strange things”



…or something like that.

Here are some sentences with the word 好奇心:

kare no koukishin ni wa kagiri ga nakatta
His curiosity knew no bounds. – Tanaka Corpus

kare wa koukishin no tame ni ayauku inochi wo ushinau tokoro datta.
His curiosity nearly cost him his life. – 研究社 新和英中辞典

toutou koukishin ni kararete hako no naka wo nozokikonde shimatta
Finally curiosity got the better of me and I looked into the box. – 研究社 新和英中辞典


The other half, 旺盛 (ousei) kind of means like “brimming with; overflowing with.”

This is a really cool word, because you can attach it to other words to mean “brimming with [word].”

The most common forms of this are 好奇心旺盛 (“brimming with curiosity”), which we’re looking at in this lesson, and 食欲旺盛.

食欲旺盛 (shokuyoku ousei) means something like “having a huge appetite.” In other words, wanting to eat a lot.

食欲 (shokuyoku)means appetite, and 旺盛 (ousei)means “brimming with,” so it kind of makes sense, yeah?


kare wa shokuyoku ousei da.
He has a good appetite. – Tanaka Corpus

kimi wa koukishin ga ousei da ne.
You are really full of curiosity, aren’t you. – Tanaka Corpus

I have only ever heard these two uses of 旺盛 being attached to other words, but Rei assures me that it’s okay to say other things… just not common. For example…

kondo no shinjin wa, charenji seishin ousei de ii ne.
I like the new guy. He’s not afraid to take on challenging work. – Tanaka Corpus

Curiosity Killed the Cat… in Japanese

I was trying to find some idioms or proverbs about curiosity in Japanese, but I couldn’t really find any.

I looked up “curiosity killed the cat,” but it seems like there’s not really a similar proverb in Japanese, because it seems to get just directly translated:

Curiosity killed the cat.
koukishin wa neko wo korosu
(This is a literal translation. Usually when Japanese dictionaries use these brackets 《》, it means that that’s the literal translation… as in, people don’t say it. I took this definition from a small article written in Japanese about the English phrase “curiosity killed the cat.”)

I did find a somewhat similar proverb in Japanese, which is translated to this phrase:

koukishin wa mi wo ayamaru
Curiosity killed the cat.

I asked Rei if she’d heard it before. She said that it sounds familiar, but she’s not sure if she’s heard it before. To me that means, No, nobody uses it.

As a side note, the phrase 身を誤る (mi wo ayamaru) is kind of interesting. It directly translates to something like “to mistake (誤る) one’s body (身),” but actually it means something like “to stray from the straight and narrow.”

Examples from Japanese dictionaries…

akuyuu to majiwaru to shirazu shirazu no aida ni mi wo ayamaru
If you keep bad company, you will drift into error. – 斎藤和英大辞典

kare wa mi wo ayamatta ageku satsujin made okashita
He went to the bad and ended up committing a murder. – 研究社 新和英中辞典

Finally, here are some examples of 好奇心旺盛:

kare wa koukishin ousei da
He is full of curiosity. – Weblio Email例文集

kare wa totemo koukishin ousei na kodomo datta
He was a child brimming of curiosity. – Weblio Email例文集

It’s also okay to separate 好奇心 (curiosity) from 旺盛 (brimming with; overflowing):

kimi wa koukishin ga ousei da ne
You are really full of curiosity, aren’t you. – Tanaka Corpus

koukishin ga o-ousei na no wa taihen ni kekkou na koto de aru
A healthy curiosity is truly a fine thing. – Tanaka Corpus
(This sentence sounds extremely stiff and formal.)

Curious About Your Thoughts

If you think these kinds of articles are interesting, please let me know in the comments or via email! I’m trying to add more practical information about the Japanese language these days.

Also, comments and questions of any type are always welcome, as always.

Keep swimming,


p.s. Don’t forget about this lovely bundle of goodness:


Yo! I'm Niko, the founder of NihongoShark. I'm also a Japanese translator, writer, and all-around language nerd.

I created this site to help as many people master Japanese (any language, really) as possible.

Uh, what else? Well... I live in Tokyo, Bangkok, Sapporo, Saigon, San Diego, Tokyo, Chiang Mai, Portland, Oregon! So if anyone wants to meet up for a refreshing nama beer, I'm probably down for that. Or a coffee. Learning Japanese is tricky-tikki-tavi. But we're in this together. ファイト!

Good luck with your studies!


p.s. If you like my articles, you may very well love my daily lessons.