A good password has entropy, which is not a property of the alphanumeric string but of the process used to create it. Could your password generation method plausibly have produced 2^60 alternative passwords with equal probability? Probably not.
Also, never reuse passwords.
ペルソナは心の力 - read as "perusona wa kokoro no chikara"
Then I've replaced it with the English spelling of Persona -> "persona wa kokoro no chikara"
Then I replace chikara with a misreading - when I first learnt the characters, I mixed up 力 (chikara) with the katakana カ (ka) and often read both as ka -> "persona wa koroko no ka"
Then remove the (unneeded) spaces and add a "!" for good measure -> "personawakokoronoka!"
Dead easy for me to remember, but (I believe) difficult to derive/guess or dictionary attack (especially if I start with a longer sentence).
Or maybe "One And ring in to the rule darkness them bind all, them." in that it applies a personal transformation rule.
Or do both.
It's not as secure as other methods of password generation, but makes yours more resistant to (unabridged) dictionary attacks. If an attacker learns your personal salt, they could create a special dictionary attack just for your passwords, but this is another case of not outrunning the tiger when you can outrun your friend. Far easier to run the vanilla dictionary attack against everyone else who doesn't salt/transform.
Which is longer, the alphabet or the dictionary?
There's a hell of a lot more words in any language than there are characters that make them up.
N case insensitive words is far better than N character password from the normal set of characters (alphanumeric + special characters).
Even if you restrict the combinations of words to grammatically correct sentences there's still more combinations than there are of for the same number of characters
That still holds even if you make assumptions about sentence structure, common word combinations, etc, etc. There's a lot of words out there.
You're using an analysis for random words, which is completely different.
Also in general a random word is worth around as much as two random characters. There's no clear-cut winner, use whatever you like more.
This is the main problem and we created this problem. Over the last 30 years we worked so hard to make passwords weird and not even that hard for computers to try find. If your password is a sentence that you know by heart, say your favorite quote, the motto of your country, of your school, or some cool fact etc... your password would be (1) safer and (2) easier for you to remember. That's what I do and I never have hard time remembering my 4 to 6 word password. I just use bunch of books/movies and remember my favorite quotes. For example "one ring to rule them all" is a good password, or "may the force be with you" or "call me ishmael".