Description

Old description:

L8gnk0GgYm9cCAA5t7wSIcwc669T+2TY/KlK4ATmQsnVrSY3PWrXAwUPcJiN1AugpkVwkDQARQydWkbLvs+4V0I08mSQKRsDinKZchmMlTJY8KCCS4ZDof1BxuCB7Uab6rAitGRYl+KgXqvROEbCWfb80nsDNaqo6wavnAVX5ld3nD6Ykl0vKIUUVNxuE42xDiMYuENg+tFLwsKcUzuw2KNZ+st46FBkZBniKP5jVQrqZzqAzgvcpHR63yMOZPkWMrVBHBwCRS31GRVx5qpzoB+0dkP0vX+YugYKIе9HvkEFJ440PCpMSd3ITK5Zmq/YJfAg5YyNpmRod3b2MVOfhX35lkjg41+4bidTo4H4d8sTiNz7YD74a5tWuzCj6BXax7ErPueqA7uRCcjaNXnGGrDLaFsEQkpFKWRmWm3hItAF5FiTqfB//7zj10iWCBDt3jJ1uNhrFLG7SX8kpvFyuw==
[Key: **************G4]

Old title: "̷͔Ͱ̴΁̱ͭ;͉͌ͪ͊ͦͥ̀Ά͑΅ͳ΂΁̿Ϳ͉̻̽ͫͻ̸͕͸ͦͶ̳Ί͐͏͎͟΋̹͜΂·ΆͿ΄ͽ̓΁ͺͿ͸̾͟͞ͺ͹͸ͱ̷̶ʹ͖ͲͫͰͩͨΌ͎͍ͬͩͨͧ͟͠΃͚͙͖͛͢͝͞͝ͺ͚͙͑͐͘ʹ̷͓͒".

Old title (escaped):

\u0354\u0337\u0370\u0334\u0381\u036d\u0331\u037e\u034c\u036a\u034a\u0349\u0366\u0365\u0340\u0386\u0351\u0385\u0373\u0382\u0381\u033f\u037f\u033d\u0349\u033b\u036b\u037b\u0338\u0355\u0378\u0366\u0376\u0333\u038a\u0350\u034f\u034e\u035f\u038b\u0339\u035c\u0382\u0387\u0386\u037f\u0384\u037d\u0343\u0381\u037a\u037f\u0378\u033e\u035f\u035e\u037a\u0379\u0378\u0371\u0337\u0336\u0374\u0356\u0372\u036b\u0370\u0369\u0368\u038c\u036c\u034e\u034d\u0369\u0368\u0367\u0360\u035f\u0383\u035d\u0362\u035b\u035a\u0359\u035e\u035d\u0356\u037a\u035a\u0359\u0358\u0351\u0350\u0374\u0337\u0353\u0352

New description:

def shift_characters(message):
    return ''.join([char if char == ' ' else chr(ord(char) - 1) for char in message])

message = "hello world!"
while True:
    message = shift_characters(message)
    print(message)

New title: [Filtered]

Noise

The Hiyori image is always decomposed into 2 images with 0.5 opacity, then each line of each image gets put to a certain position on-screen. If the 2 images overlap, they blend.

The pattern is regular, but very complex. It’s possible to undo some of the mangling, as seen here, but further analysis of the mangling algorithm is currently ongoing.

Solution

The code in the new description hints at shifting the characters. Indeed, all characters are from the same range, and when shifted down by 784 Unicode codepoints, the title becomes the following Malbolge program:

D'`$q]!n<Z:9VU0vAucrq/o-9+[k(EhVf#z@?>O{)Lrwvotm3qjoh.ONjiha'&dFb[`YX|\>=YXWPOsMRKJINMFjJIHA@d'CB

This program prints “hello wo” and exits. However, if we use a Malbolge generator to generate a program that prints “hello world!”, we can recover the missing piece at the end - ;:9]7<54981U543s+O)o-&+*#G4.

The description says [Key: **************G4], and the Malbolge program indeed ends with G4. If we take the last 16 characters, we get the AES decryption key.

CyberChef link

Answer

[FILTERED] ALWAYS TELLS ME SHE WANTS TO BE A VTUBER ONE DAY. SHE’S OBSESSED WITH THEM AND EVEN HAS HER OWN CHARACTER THAT SHE WANTS TO DEBUT AS. THAT’S ALL SHE EVER TALKS ABOUT. SHE SPEND MORE TIME IN THE [FILTERED] INSTEAD OF PLAYING OUTSIDE WITH EVERYONE ELSE. A TRUE INTROVERT… WE ARE IN MORE WAYS SIMILAR THAN I LIKE TO IMAGINE…

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