Previously in the comments
I received a request saying
"Please write an article when you use the Unko Harigane X again!"
I mean, who benefits from this...?

Also, the owner of the bike whose chain I was replacing
said "I'd like to see my bike's parts featured in an article"
so I wrote this post.

With Campagnolo chains, you need to pass the connecting pin outward.
By crimping it with the specialized tool, the resulting protrusion
is kept from interfering with the sprocket and such.
This type of tool is really convenient for doing that job.
I've been using it for about 10 years, and it's true that you don't lose things you really need.
I've tried several times to make a similar chain hook from a spoke,
but the chain roller doesn't catch it properly and it slides off,
and somehow I can't make anything that works better than this one.
If you actually try it, you'll understand—
bending a spoke into this shape is extremely difficult in itself.
(Whether you even need to bend it into this particular shape is unclear)

Spokes and wire in general have this habit where, as you're bending them,
they sometimes accidentally end up looking like something by chance.
We actually almost went out of business once because of that (for details, see here).