Harvesting Oni-gurumi in autumn of Yokohama

An entry in the Bucket List of mine is visiting the forest of walnuts in Kyrgyzstan. The walnuts’ origin is somewhere in the Central Asia. The village of Arslabob which looks like (in the map) almost the beginning of Ferghana Valley has the world’s largest wild walnuts forest. According to a guy from CBT Kyrgyzstan, they have several tourism packages to enjoy the place which takes 3-4 days by horse ride … Someday … Oh, yeah. The walnuts over there, or the nuts we find in supermarkets normally are so-called English / Persian / Californian walnuts. We can enjoy them with a nutcracker, right? A-hem, in Japan, there is another kind of walnut, juglans ailantifolia, in Japanese “Oni-gurumi 鬼ぐるみ.” Translation: Devil’s walnut. No, no, it is not something with poison. Oni-gurumi is Japanese native small walnut whose size is about 2/3 of their continental cousins. i.e. very Japanese. Though, I personally think the flavor of oni-gurumi is richer than common walnuts. They are DELICIOUS! (and expensive: my recent market research found average 900 yen per 60g of oni-gurumi). Then, why is it called Devil’s nuts? Well, try your nutcracker for them, and the tool will be broken. I mean, not a broken nutcracker in Tchaikovsky-way, but probably the whole head of the doll would be destroyed by the Devil, and the ballet will be more of a zombie movie. Oni-gurumi has an extremely hard shell. There is a trick to open the shell ;)

To crack the nut, literally, we should start from oni-gurumi’s life in the forest. In Niiharu Town, along Umeda River, I know there is at least one oni-Gurumi tree. (I don’t tell you where exactly, ha ha ha.) And near Zoorasia, along a small stream, there are two huge oni-gurumi trees that are famous among locals … Got it? Yes, in Yokohama juglans ailantifolia grow by streams. Basically, the plant grows at the edge of a mountain stream, and depends on running water for its nuts/off-springs to spread. I know a bank of moderately large river in Yokohama that have lots of juglans ailantifolia, some large with more than 20m tall, and babies of 1m or so. As I can find so many oni-gurumi trees there, I was curious what kind of forest I can find in its upstream. It soon became apparent the source of the river is now in a well-manicured city park of Tokyo. The embankment of the river is completely controlled from the start to Tokyo Bay in order to protect the sea of suburban houses both sides … Perhaps, before the World War II, the river ran rapidly within the sea of forests where many juglans ailantifolia situated themselves at the border between the land and the water. The oni-gurumi trees I can find now must be the descendants of them. By the way, there is another “gurumi (kurumi)” called in Japanese Sawa-gurumi / pterocarya rhoifolia that come out by streams in Japanese mountains just like oni-gurumi trees. This one does not produce edible nuts. If you ask about oni-gurumi to Japanese, many people would answer about Sawa-gurumi, which is confusing.

One of moderately tall oni-gurumi trees stands
just next to a large river-side condo.

As I can find so many trees of tasty nuts too near to huge towns where it seems to me not many people notice the situation, I thought I should clear the legal matters first. I emailed the City if I can harvest nuts a bit from the trees sprouting in the embankment. Their answer was as the river and its bank in question is under the jurisdiction of Kanto Development Bureau for the Ministry of Land, Infrastructure,Transport and Tourism, I should ask about it to them. OK, so I wrote an email to the Bureau for the same question. The reply I received was, as they are delegating the management of this river to the City of Yokohama, I should ask them ……. It’s so called “Typical!” situation with bureaucracy … Weeeeeeeeeeeell, as “I am a thoroughly good girl,” I made an enquiry to a policeman stationed for the police box in my neighborhood. “Hmmmmm, it would be a question falls in a grey area.” He said. “In such a case, the common sense approach should work. Unless you harvest the oni-gurumi in industrial scale, or damage the trees on the bank, I think you could have a good stand, legally …” Hmmmm. So, one early autumn morning every year, I’ve been there to have a “modest amount of walnuts” for my family.

The place where MLIT delegated the job to the City …

Harvesting ^.^
When the (possibly year’s) last typhoon has gone and
the smell of osmanthus fragrans var. aurantiacus starts wafting,
it is time for oni-gurumi collection.

I think it is modest enough.
In any case, I left lots of nuts on the trees.
Sharing is important …

Sure, you can try to remove the outer membrane of the fruit by hand, or I should say by force. Believe me, you cannot reach to that familiar shell of walnuts in this way with oni-gurumi. Your hand-shredded mesocarp sticks to the nooks of the walnut stone no matter what. Moreover, the outer layer of oni-gurumi was once used to dye fabrics in brown so that your trial to get rid of the fleshy part of a fruit makes your hands and fingers dirty yellow. It is difficult to remove the color for days. Now, we have to recall how the tree tried to spread its seed afar. It used the stream, right? So, let’s just simply soak the fruit in a bucket of water. After 10 days or so, the fruits naturally separate its fresh from the stone. Hello, lovely walnuts. Nice to meet you! It would be the way oni-gurumi obtained during its evolution to facilitate germination. By the way, the dye from oni-gurumi membrane is with pedigree. In the Tale of Genji written in the 11^th century, there is a mention where the correspondence between elegant Lady Akashi and the playboy prince Genji was done with papers “dyed by walnuts,” i.e. by oni-gurumi. For the methodology to dye fabric with oni-gurumi membrane, please check here.

Soaking the harvest.
You’d better make an insertion with knife
on the green membrane before soaking.

Like this.

I wore work gloves just for soaking,
and my fingers ended up with stains.

Two days later. The water had this color.
We can use it to dye fabric.
This site says protein-based material such as silk or wool
could respond well, but cotton or hemp does not.
The hue could be dramatically controlled by the choice of mordant.

10 days later.
Could you see the changed color of the fruit meat?

We can just twist a fruit along the knife,
and the nut comes out easily now.
My rubber gloves have been dyed already
with the walnut fruits.

The flesh of the fruit and the nuts

The water turned into this color after 10 days.
I guess we can use it to dye the fabric as well.
Or, we mash the fruit, cook the paste, strain the liquid, add mordant …

The nuts must be washed to remove the fibers
running along the seam(s) of shells.
This devil’s treat refuses to open the mouth with roasting
when the fiber remains along the seam.
Could you see the fibrous things in the water?

Done!
Oh, this brush is traditional Japanese (kamenoko-tawashi 亀の子たわし)
made of the bark of hemp palms ubiquitous in the forests.

You may think you can leave the cleaned oni-gurumi stones nicely in a cute bowl, and crack them during Christmas holiday as with the standard English walnuts. Wrong approach. Once the stone is dried, they close their natural crack so tightly that without smashing the entire stone in pieces we cannot have nutmeat. The trick is, while the nuts maintained the moisture after soaking, put them in oven, and bake them at 150-160ºC for about 30 minutes. Look for the sign where steam comes out from the slightly opened seams. The oni-gurumi is ready to be cracked now. Use your minus screw driver or some tool with strong metal, to pry open the stones. Knives are risky for this operation. If they are large with strong blade, it is tricky to deal with small oni-gurumi. If they are small hand knives, the blade could be snapped easily and cause serious harms. Also, don’t wait too long for the stone to be cooled completely. The tiny opening thanks to the steam will be firmly shut when the inside air returns to the room temperature. Time is the essence for dealing with oni-gurumi …

Roasting oni-gurumi.
Could you see the steam comes out,
and the seams are slightly open?
They are now ready.

Mise en place to crack oni-gurumi

Another way to use “screw” driver
If some nuts do not have an opening,
re-roasting 5 more minute would do the job.
Caution: don’t overdo it.
The nut meat could be burned with too much roasting.

Opened walnuts
Now, we need to pick the meat out.

Like this.
Could you notice the hulls in the background
do not have any insect holes?
I have never encountered a worm-eaten oni-gurumi.
Their hulls are at least 3mm thick,
and probably insects don’t bother to reach to the meat.

This year’s harvest
They can be eaten as they are,
or used for any recipe with standard walnuts.
They look containing lots of oil, don’t they?
In order to prevent their nutritious fat to be gone bad,
I always freeze them for storage.

My experience told me this contact address is not useful for oni-gurumi … Anyway, the City Office who’s in charge of execution of Green-up Plan is

Yokohama Municipal Government Creative Environment Policy Bureau 横浜市環境創造局

Phone: 045-671-2891

FAX: 045-641-3490

http://www.city.yokohama.lg.jp/kankyo/