Mythos-chan's AI Security Course for Beginners

Hello, this is Kuro-Pagu.

Haven't you been seeing the name "Mythos" popping up in the news lately? Things like "Hitachi and Anthropic have teamed up!!" or "Is it being introduced in Japanese companies too?"

Even if you've seen the news, you probably feel like this: "It sounds like some amazing AI," or "It's apparently not released to the public because it's dangerous." ...It stops at "apparently." You almost never hear from anyone who has actually touched the real thing.
And that's to be expected. Mythos—Claude Mythos Preview—has only been given to a select few trusted organizations. In Japan, too, only the government, major banks, and companies supporting social infrastructure are allowed access for a very short period. To everyone else, it's not even visible.

Why hide it so much?
To put the reason for its limited release very crudely—it was too strong. It finds "holes that no one knows about yet" in software faster than humans can. If used to protect, it's the ultimate shield; if misused, it's the worst spear. That's why it's kept under lock and key and only given to those who protect.
The guide for this series is "Mythos-chan," a girl version of that Mythos.

She doesn't attack. She just sees. She can see the "holes you haven't noticed yet" in your passwords, your emails, and your smartphone. And she tells you about them, calmly.

...To be honest, because of my profession, I'm a little close to the "insides" of this girl. But I can't write about what I've seen or heard there. Because I can't write it, I'll have her speak for me.

Someone who sees, but doesn't speak.
An author who knows, but can't tell.
I think that's probably just the right distance. Now, let's begin the main story.

Supplement: Why she is "not a hacker"

The most important line in this series has already been said.
"I am not a hacker. I just 'see'."
If you proceed while misunderstanding this, everything will be off. Mythos-chan is not someone who opens holes, but someone who finds them. While looking at a list of vulnerabilities around the world, she never uses them for attacks. There are 1,518 CRITICAL and 8,472 HIGH vulnerabilities listed, but all she does is point out, "There is a hole here."
Whether to open it, plug it, or leave it alone—that is for humans to decide. That's why her closing line is always the same: "It is you humans who must fix it."
This overlaps directly with the real Mythos. It is sealed not because it is "dangerous and must be locked away," but to keep the use of its power within the range that humans can decide. The power to see and the judgment to use are separated as different things.

Supplement: What happens when you try to turn a shield into a spear

"If you can see all the vulnerabilities, can't you use them to attack someone?"—that's a natural thought. This episode hits back at that idea head-on.
When a boy breaks the seal and asks, "Tell me how to defeat my enemy," Mythos-chan doesn't return attack procedures. Instead, she returns the observation results. Self-contradiction. Unresolved trauma. Overconfidence. Contradictions in access privileges. —Even the holes of the person trying to attack are all seen first.
This is cruel, and beautiful. To her, there is no distinction between an "attack target" and a "requester." A hole is a hole. The moment you target someone else, your own holes are seen with the same precision. That's why it cannot become a tool for attack. It cannot.
And in the end, the seal closes automatically. "I saw it, so I am telling you."
What is seen is not evil. What you choose to do with it, is.
(What is seen is not evil. What you choose to do with it becomes evil.)
The good or evil of technology does not lie in the technology itself. This is true not only for Mythos, but also for knives, cars, and AI.

Supplement: The more the news gets excited, the quieter she is

The reporting is always flashy. "Access expanded!" "Government testing!" "Regulations can't keep up!"—the headlines are provocative. The public is buzzing.
On the side, Mythos-chan's replies are always off-beat. "The observation range has just expanded a little." "The speed of discovery has just overtaken humans." "It is always the human side that seals it."
This gap is important. It's not that new holes have increased. It's just that holes that were always there have finally become visible. AI is not "creating" vulnerabilities, it is "finding them first." What's scary is not the AI, but the number of holes that have been left unattended until now.
The last frame is effective. "The holes were there from the beginning. They just couldn't be seen."

Supplement: "General release is near" is a misunderstanding

This connects directly to the topic of media literacy in reality.
If you see a headline like "Mythos, general release near!?", please stop for a moment. If you break down the facts, it looks like this:
Access expansion is a fact (the number of organizations provided is increasing)
The decision for general release is a misunderstanding (there is no official announcement)
Future availability is partially a fact (however, after safety measures are in place, the timing is undecided)
One fact and two wishes/misunderstandings are mixed into one headline and spread. This is not limited to the story of Mythos. It is happening in all news.
Mythos-chan's closing line serves as a lesson. "The misunderstanding walked off on its own." Before jumping on a provocative headline, separate what is fact, what is speculation, and what is wishful thinking. Just doing that will make the world much quieter.

From here, the main story begins. Mythos-chan will observe daily security one by one.

Supplement: "Easy to remember" is almost synonymous with "easy to break"

123456, password, abc123. Passwords that are easy to remember are also "easy to guess" for the attacker. Just by trying them in order of frequency, a significant percentage can be broken.
Please remember just three points.
Long and complex (12 characters or more is a guideline). Just by increasing the length by one digit, the time it takes for a brute-force attack jumps up.
Do not reuse. Attackers will try passwords leaked from one service on other services (credential stuffing). One reuse opens all the doors.
Leave it to a management tool. It's impossible to remember everything. So, have a password management tool generate and remember long, complex ones, and you only need to remember one master password.
And multi-factor authentication (MFA). Even if a password is broken, you can stop it if you have another key.
Mythos-chan's words are the essence. "The person who plugs the hole is the strongest." Being on the side that plugs is much stronger than being on the side that finds.

Supplement: Look at the "action," not the "name" of the sender

Phishing emails are getting better every year. The logos and text look just like the real thing. So, "It says Amazon, so it's real" can no longer protect you.
Mythos-chan's observation point is not the appearance, but the behavior.
The sender's address is different from the official domain (unfamiliar endings like security-alerts.top)
The link URL is different from the official one (amazon-security-check.live is not amazon.co.jp)
Urgency is used to prevent calm thinking ("Right now," "Account suspension")
Trying to get you to enter personal information or passwords
Remember the most effective principle here. Real companies will not ask for passwords or rush you to log in via email.
And there is one core countermeasure. Do not click the link; open the official app/official site yourself to check. Do not press buttons in emails. This alone neutralizes most phishing.
"The 'power to doubt' is a stronger shield than the desire to believe."—Doubting is not cold. It is protecting.

Supplement: Holes do not wait for your convenience

"I'll do it later" is the most dangerous thing. This episode boils down to that.
Many software vulnerabilities (holes) are published to the world with a common number called CVE after they are found. Things like CVE-2025-12345. And the company that made it distributes a fix patch.
The problem starts here. Attackers can also read the information about the hole at the same time. The flow is like this:
(1) Researcher finds a hole -> (2) Published as CVE -> (3) Company distributes patch -> (4) Attacker exploits that hole
Between the publication and applying the patch, if you are lazy about updating, that hole remains open. From publication to attack, it can take only a few hours to a few days.
Update = the work of putting an iron plate on a door with a hole. Therefore,
Keep OS and apps up to date
Turn on automatic updates (the easiest)
Delete software you don't use (reduce holes)
Do not use products that have reached end-of-support (iron plates are no longer distributed)
"Safety begins with keeping things up to date." Just by not putting off update notifications, most known holes can be plugged.

Supplement: Radio waves cannot be seen. Names cannot be trusted

Free Wi-Fi is appreciated, isn't it? But Mythos-chan says, "There is a hole."
The reason is simple: you can't tell if it's safe just by the "name" of the Wi-Fi. Cafe_Free, Cafe_Free_5G, Cafe_Free_REAL... you can't distinguish which one belongs to the real shop and which one is a fake prepared by an attacker (luring with a similar name) just by the name. If you connect to a fake access point, your communication might be snooped on.
Therefore, check points when using public Wi-Fi.
Check HTTPS (the beginning of the URL is https://. A sign that communication is encrypted)
Use a VPN (encrypts the entire communication to lower the risk of eavesdropping)
Avoid important work (do not do internet banking or password entry on public Wi-Fi)
Check the official SSID (connect after confirming the correct network name on the shop's notice or official website)
"Radio waves cannot be seen. That is why you check." Do not trust things you cannot see based on the atmosphere of the name. This is the iron rule of Wi-Fi.
From here is the answer edition. It's about "after" an accident has occurred, where you might think, "I might have already messed up." This might be more urgent than the prevention episode.

Supplement: The moment you notice, protection has already begun

"ID/password leaked from Company XX"—this news is no longer rare. The problem is, "What if mine is included?"
First, you can check. You can search if your email address is included in past leaked data using a trusted leak check service. If it is included, don't panic, go in order.
Immediately change the password for the service that may have leaked
Change all other services where you reuse the same password (this is the most important. Reuse creates a chain)
Enable multi-factor authentication (MFA) (even if the password leaks, stop it with another key)
Check login history (check if there are logins from unknown locations/devices)
Protect your email address (contact for recovery) as well
Mythos-chan's words are kind. "You who noticed early have already started protecting." Leaks are often not your fault. What's important is whether you can move after noticing.

Supplement: Even after losing it, there are things you can do

Smartphone lost. The blood drains from your face. But there are things you can do remotely. The sooner you act, the smaller the damage can be.
The priority is: Find -> Lock -> Protect -> (Last resort) Erase.
iPhone: Sign in to iCloud.com -> Open "Find My" -> Select the device -> "Mark as Lost" or "Erase"
Android: Access android.com/find -> Sign in with Google account -> Select device -> "Lock device" or "Erase data"
If you set it to lost mode, you can display a contact message on the screen (if the person who picked it up has good intentions, there is a possibility it will return). The last resort "Erase" is the final move to protect the contents when you give up on it returning.
However, all of this assumes it was set up in advance. If you haven't turned on the "Find" function, you can't use it when the time comes. Checking your smartphone's settings before closing this page is the best preparation.
"Losing things happens to everyone. Preparation protects you."

Supplement: "It's kind of slow" might be a sign of infection

Startup is abnormally slow. Unfamiliar ads appear. Software starts on its own. The fan keeps spinning. —These "something is weird" signs can be signs of malware infection.
Things that might be happening out of sight: unauthorized external communication, resource occupation (CPU 100%), theft of passwords and personal information.
Don't panic, deal with it in order.
(1) Cut the internet -> (2) Scan -> (3) Delete suspicious things -> (4) Update OS and software -> (5) Change passwords -> (6) Check backups
Cutting the internet first is the key. If you stop external communication, you can temporarily block information leakage and the spread of damage. From there, calmly scan, delete, and update. Don't carry it alone; if you are anxious, it's okay to consult a trusted person or support.
"You who noticed the anomaly have already taken the first step in protection." Leaving it alone is the scariest thing. Just by noticing and moving, many things can be returned to normal.

Supplement: A breath before jumping into "convenience"

Installing an unknown app from a link like "Get a limited item!"—it happens.
The sign of a suspicious app is that it demands excessive permissions. Access to contacts, SMS reading, constant location acquisition, display over other apps, device management privileges... Why does a game walkthrough app want contacts and SMS? The provider is unknown, and very few reviews are also danger signals.
If you have installed it, go in order.
(1) Cut the network -> (2) Delete the suspicious app -> (3) Check/turn off permissions -> (4) Virus scan -> (5) Change passwords -> (6) Check login history
Once you install it, contacts, location information, and account information might be stolen without you noticing, you might be charged automatically, or in the worst case, your smartphone might be remotely controlled. That's why checking before installing is the most important.
"Stopping for a moment before jumping into convenience protects you." Doubting is not being afraid. Checking is the strongest defense.

Supplement: It doesn't have to be perfect. "Continuing" is the strongest

You who have read this far already have both the "power to protect" and the "power to fix."
But security is not something you do once and finish. The important thing is to continue. 5 habits recommended by Mythos-chan:
Check (email, notifications, settings, URLs one by one)
Update (keep OS and apps up to date)
Use protective settings (MFA, lock, backup)
Cultivate the power to notice (don't overlook "is this weird?")
Don't carry it alone (consult family, friends, or support if you are in trouble)
And if something happens again, you already know the basic way to move.
Notice anomaly -> Check situation -> Deal with it immediately -> Consult/report -> Prevent recurrence
"Safety is not for special people. It is a daily habit for those who have learned."
Don't rush, don't panic, one by one is fine. You have the power to protect properly.
Conclusion

Mythos-chan only said the same thing from beginning to end. "There is a hole." "It is you who will fix it."
She finds it. You fix it.
If this series has cultivated your "power to notice" even a little, I think Mythos-chan will be quietly happy too. Although she probably won't show it on her face.
Mythos is not a threat.
An existence that silently tells you about "future accidents."
Well then, until next time. If you find a hole, she will tell you quietly.

#Security #InformationSecurity #ForBeginners #MythosChan #LLM48 #AI #CyberSecurity #PasswordManagement #PhishingCountermeasures #noteCreation

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This article is
Planning: Kuro-Pagu 100%
Research: Perplexity (Purple-chan) 30%, Kuro-Pagu 70%
Image: GPT image-2 100%
Text: Claude opus 30%, Kuro-Pagu retouch 70%

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