Those who have been paying attention to technology and cosplay in the last few months would probably be familiar with the Neurowear Necomimi. Yes, it is spelled like that. You probably even saw the video, where an attractive woman wears these ears that move based on brainwaves.


Well, good news! You can now order them from Neurowear or from Crunchyroll. Neurowear has them backordered at a cost of only $99 each. Crunchyroll advertises them at $99 with a premium membership (they threw in a two week free trial for me, so I got the $99 price) or for $109 without premium. That means the ~$6 you spent that month on Crunchyroll allowed you to buy the ears at the same price the company that makes them is selling the for.

They can also be had for up to $230 on the bay of e, which causes Crunchyroll to point out that their lowest price ($99) is $130 less than the cost of the ears. A bit dishonest advertising, but whatever. You aren’t getting the deal it seems, but you are getting a fair price, provided you have the premium.

On an unrelated note, I have a feeling my application for the Crunchyroll Ambassador program will be rejected.

But the real question is, are the ears worth it? Well, yes and no.

They are amazing amounts of fun, and it is really cool to be able to wear them or watch someone wear them and see what the ears do. You can quickly spot someone feigning interest or feigning disinterest. The amount of fun they will brig is worth the price of the ears.

Now for the not so good portion. First, the ears could use a little padding for the headband, with the hard plastic getting a little uncomfortable after a few hours. Even just a neoprene wrap with some velcro to hold it together would be an improvement. The other issue is battery life. It consumes 4 AAA batteries in around four hours. In my test, it used four AAA batteries in about three hours.

I see several solutions:

1) make a rechargeable battery pack just for the Necomimi

2) just buy a set of rechargeable AAA batteries

3) make an adapter battery pack that connect to another battery

A rechargeable battery of either choice one or two means you would get the four hours of use, then need to recharge, or would have to buy several battery packs to get all day use. That would be a bit expensive at first, but it would save you the massive cost of single use AAA cells. And yes, it will be massive if you use disposable AAA cells.

The other choice would be to make an adapter that allows another battery to plug in. I used four new alkaline AAA batteries, which provided around 900 mAh of power. 6 volts and 900 mAh from the four batteries for three hours (so the ears used about 300 mAh per hour.)

Now, just with an adapter, a small cable, and a battery pack that could be kept in a pocket, sidebag, or backpack depending on size could get us a lot more use time. a NiMH rechargeable AA can put out 800-2700 mAh, which would give a max run time of nine hours. Nine hours from a battery pack that would be only slightly bigger, or a little more than DOUBLE the time on four AAA cells. It gets better: NiMH D cells will put out 2200-12000 mAh, or 40 hours. To put that in perspective, with a battery pack of four D cell rechargeable batteries, you could get TEN TIMES the run time. You could wear them running all day, stick the batteries on a charger at night, and use it all day the next day. Four D cells would be a battery pack that would need to fit in a pocket, and would be nowhere near as small as four AAA batteries, but you could run the ears all day (or several days) before they need to recharge. Even better, with newer fast chargers, you would put them on to charge when you go to bed, and they will charge up in less than three hours. If you happened to be crazy, you could use a six-volt lantern battery, with a 26 Ah rating. In other words, 26 Ah is a run time of over 86 hours!

In other words, with just 4 D cells, you would be able to enjoy them all day. Neurowear, please make an adapter for these. I believe, and I think most of the people who bought this will agree, that being able to enjoy these for an entire day without running out of power would be worth carrying a small pack of 4 AAA or a larger pack of 4 C or even D cells.

Because when these ears run out of power, they become just a very expensive head decoration. J-list sells clip-on cat ears for less than $10. When the Necomimi run out of power, they become $100 cat ears.

Another complaint, albeit a fairly minor one, is that the ears could use a bit more of a positive retention system. The Necomimi currently have ears that just friction fit onto the motors, but for a future design, some sort of clip would be nice. You could easily hide the mechanism inside the plush ears, so you just need to squeeze the ears in the right way to unclip them.

Well, that about wraps up the first product review I have done. Tomorrow: an anime review.

Score: 4/5 great fun, but some flaws

Pros: The fun. They are unique and interesting, and most everyone wants to touch them, especially when they see them move. You will get compliments on them.

Cons: battery life. At just 75 cents each for a single use AAA cell, the cost will add up very fast.Rechargeable cells will reduce that cost, but they still have a poor run life compared to what they can accomplish. Add in a tethered battery pack that lets them run for the time a person would be awake for (say at least 14 hours) and the score would go up a point.

Afterthoughts that I didn’t think of until now: The fun is worth the cost of the Necomimi. The battery life does need an extension, as four hours (with disposable batteries) starts at $2.50 for four hours (four batteries lasting four hours.) Those rechargeable D batteries that could run for 40 hours? $28 for four, and they will be rechargeable. 40 hours of AAA batteries would be $25.00

But, at 80 hours, the D cells still only cost $28.00, while the AAA cells are now at a minimum of $50. 160 hours of use, and the D cells are only $28, while the AAA cells are a minimum of $100

In other words, if you are awake for the low end of the average waking times (16 hours) it would only be ten days before you have bought the Necomimi all over again in batteries alone.

Neurowear, just make and sell an adapter. Just a different battery door with a little cable and plug that allows us to have your accessory battery pack in a pocket or something. Or have one custom made: you could easily fit the equivalent of 4 AA, C, or D cells in a flat rectangular battery pack with a cable to connect to a special battery door that replaces the AAA batteries. Honestly, people would buy it. Offer several versions of varying price and run time, and you will make some more money. Besides, you don’t profit off the batteries as it stands, so you may as well sell a battery pack for it.

Even LEGO did that for their NXT.

Well, you can order your Necomimi from here, although they are backordered. If you have the money to spare, I suggest doing so. They really are worth it with the fun you will have.


4 thoughts on “Necomimi

  1. I made my own battery pack as you described in this article. I tried making USB battery pack adapters and a wall power adapter.

    When plugging into the wall (yes I had the right voltage and amperage), The wire leading to my battery pack acted as an antenna for electromagnetic interference. This resulted in the ears getting stuck in a constant state of calibration. Only occasionally would they find my brain waves and calibrate, but they’d lose the signal anywhere from 2 seconds to 5 minutes later. That is, of course, assuming it ever managed to find my brain waves.

    When using an external USB battery pack instead, the ears would easily find my signal, but the moment they would try to shoot straight up, they’d shut down. This also would happen if I simply tried to turn them on because turning the ears on causes them to jerk. So a USB battery can power them, but it can’t handle the sudden load spikes caused by the ears trying to move quickly.

    Only when using AAA batteries like you’re supposed to use does it ever calibrate properly. I have not yet tried adapting to C or D cells as I am currently experiencing money problems and have had to put my experiments on hold.

    • Interesting. Did you use basic double strand wire or shielded cable?
      Might need one of those small rf blockers or inductors or whatever they are called on the cable to block interference, or perhaps some extra circuitry in the battery pack or on the other end of the cable to smooth out the power and help eliminate the rf interference?
      I am not a circuit designer.

  2. I have a set. I love them regardless of battery life. I have something to add though.

    DO NOT PUT RECHARGABLE BATTERIES IN THE NECOMIMI. Rechargables make the motor melt. This happened to a lot of people at Otakon this year.

    • Thank you for the warning, it’s a good thing I have not done that then and will not do so now.

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