Daiwa has discontinued the Lupin spoons. The basic concepts of the article below are still valid, however. Please consider the Daiwa Eve spoons in 1.2g, the Forest Factor spoons in 1.2g and 1.8g, the Forest Pal spoons in 1.6g or the Shimano Slim Swimmer spoons in 1.5g. All are available on the JDM Spoons Shop page.
The Daiwa Lupin spoons are very nearly as small as the Vega spoons. They are just a bit wider, a bit more rounded, and stamped from thicker metal. Whereas the Vega spoons range from .4 grams to .8 grams, the Lupin spoons range from 1.2 grams to 1.8 grams. The difference between .8g and 1.2g may not sound like much, but it is just enough that the Lupin spoons are much easier to cast. They cast well enough that if you're fishing a relatively small stream you will have to be very careful to avoid putting them in the bushes on the far bank.
In a situation like the one shown above, you know there's a fish in there. It's a small enough pool that you need a relatively small lure that won't scare the fish when it hits the water. You'll only have one shot at it, though, and to get the accuracy you'll need, you'll want something a bit heavier than the .8g Vega spoon. The slightly greater weight of the Lupin spoons will definitely increase your accuracy.
Because they are much denser than the Vega spoons (much more weight and not much more surface area) they will also swim deeper in the water column.
If you are fishing a larger stream with deeper holes, you can get them deeper by waiting to start the retrieve and retrieving slowly. If you retrieve a spoon extremely slowly, what you think of as the top of the spoon (i.e., the orange and black side of the Orange Black spoon) will actually be facing the bottom of the stream.
On all the JDM single hook spoons I've seen, the hook is attached so that the point is up when the spoon is retrieved slowly enough that the convex side of the spoon remains facing the stream bottom. In the above photo, the Daiwa Crusader's factory barbed hook was replaced with a C'ultiva SBL-35 #8 barbless hook, but the point-up orientation was preserved. This orientation will reduce the chance of snags on either rocks or logs when the spoon is retrieved slowly.
Still, you can fish them in relatively small, relatively shallow streams and can keep them up and out of the rocks by keeping your rod tip up during the retrieve.
The Daiwa Lupin spoons come with single barbless hooks (the Daiwa Presso SaqSas #8 Speed hook). The SaqSas hooks are fine wire hooks and are just incredibly sharp. Daiwa cautions that "you should be more careful when handling." I can attest that you do have to handle the spoons carefully or that sticky hook will indeed stick you!
Even though the Daiwa Lupin spoons were designed for trout, they will catch any fish that feeds on minnows.
The hooks are sharp.
The coffee's hot.
The fish are slippery when wet.