Guy Fawkes walks into a Samurai bar...

The Katana is absolutely a meta-shaper straight out of the box. When you are learning the game, this is the ICE that teaches runners to facecheck Jinteki with caution until their killer is found. 3 net damage can set a runner back if not outright kill them. Once rezzed, the sword will keep runners who can't break it out.

Here's the little exercise that everyone does with the core set. It teaches faction strengths and weaknesses, deckbuilding strategies, AND basic math skills.

How Much Does It Cost to Get Through Neural Katana?

• Pipeline: 5
• Crypsis: 4+1
• Ninja: 4
• Femme Fatale: 3
• Mimic: ONLY 1

Ding ding ding! The cheapest-to-install killer of the bunch breaks through Katana for 3-5 times less than the competition. And Mimic only costs 1 influence, so every runner can use it! As a bonus, we also see why no one uses Pipeline.

So for your 4 to rez, you're probably getting a 1 tax per run. That's atrociously bad. So the corp learns to only rez this if it'll fire, and to just install over it if they have a Mimic on the table.

As the card pool expanded, more and more better options emerged, pushing Katana out of slottable range and onto the island of misfit ICE with Cell Portal, Matrix Analyzer, Shadow, and Heimdall 1.0.

Better AP ice would be Cortex Lock, Cobra, and Chetana. Also, Pup and Yagura have good rez-to-break ratios.

EDIT: It's notable that Katana has the highest damage of any hard damage subroutine (barring situational Cortex Lock), making it the best candidate for Batty kill). Thx @WayneMcPain for pointing this out!

Katana will probably never be used unless a Core Set 2.0 errata occurs where its rez cost is halved, or Mimic's install and/or influence costs would increase.

One of the defining pieces of Jinteki ICE, the reason it receives a high impact is because of one reason. As a Sentry, it was powerful enough to severely set the runner back if it was facechecked, (run while it is unrezzed and encounter it with no breakers but ones face) and that meant that many runners would seek out their killer before beginning a run on Jinteki.

It also is a very standard archetype for Jinteki ICE, that many other pieces like Komainu and Pup follow with, Sentry - AP ICE doing packets or streams of net damage to the runner.

While Neural Katana has fallen out of favor for more taxing ICE like the above two, or for including more ETR ICE, it has a place as a special memory, and only one other piece of Jinteki ICE can do that much damage with a single subroutine.Cortex Lock is very similar, and possibly even better early game. Katana always fell off when the Killer was found, not even being much of a tax. Cortex Lock falls off even faster even without a Killer, but can be potentially more damage. So while not a straight 'better' card, Neural Katana's situational usefulness may be better achieved with Cortex Lock

(Written during the meta of Breaker Bay, part of the SanSan Cycle. For more reviews like it, visit wyldside.blogspot.com)

Sometimes it's good to revisit old ice in light of new icebreakers.

Most ice breakers break Neutral Katana for 3 or 4. There are a few exceptions, the most important two are:

• Mimic is old and not really all that popular anymore. It breaks for 1 but hits a wall with any ice that's stronger than 3 without support. Just to name a few Assassin, Archer (more playable in Jemison), Cortex Lock, Data Raven. You don't really want to Mimic unless you have a backup plan that can breaker during the current run (i.e. not Parasite). There's just too much ice you don't want to faceplant into.
• Na'Not'K breaks for 1 if the Katana is in a two ice server (4 otherwise). Since Na'Not'K is likely to become a very popular killer for shapers and potentially anarchs as well (only 1 influence) this strongly impacts the amount of tax you can get from Neutral Katana.

While Mimic is less of a threat these days Na'Not'K is just getting started. And while as a faceplant trap the runner has to pay 4 for Na'Not'K if you have 4 in hand you can easily rez a Cortex Lock as well so a runner with Na'Not'K has to reserve 4 anyway or risk severe net damage.

Sorry Katana, but you've been replaced.

EDIT: A previous version said that Na'Not'K breaks Cortex Lock for 7. This is incorrect, even in a single ice server with just Cortex Lock Na'Not'K gets +1 strength.