As soon as the player enters Hotel Sowls, it is possible to go to the left side of the Lobby and check out bookshelves. There's quite a large variety of books the player can read by repeatedly interacting with the shelves, and some of them are even encrypted. This guide is a list of all the books and their content.

Also, I noticed it seems no one ever decoded/decrypted the mysterious books, so I went ahead and did it. Please let me know if you think any of these books are references or if I missed any books. As far as I know, all bookshelves have the same books, and all books share the same draw percentage.

">+++++++[>++S+++++[<<+>>-]
<-]>>>++O+++[>++W+++[>+++
+[<<<+L>>>=]<-]<-]<[<+<+>>-]<<
+++++++.--.>.<<.>+++++S.>+++"

This is not a proper encryption system, but rather a programming language: Brainf**k. If you enter the code and run the program, the input is "kid1ng", a Korean programmer's pseudonym. I suspect kid1ng is one of the programmers of the game, but I still need confirmation.

Special thanks to VE FORBRYDERNE for helping me discover Brainf**ck.

"Q: What changed from N0 years ago? A: There are more games that I can enjoy without being judged, regardless of who I am.
Q: Is there a game you could recommend? A: I enjoyed the game called <Hotel Sowls>, and it was-
The rest of the article is stained with ink."

"84 111 32 109 101 46
73 116 39 115 32 98 101 101 110 32 104 97 114 100 44 32 104 97 115 110 39 116 32 105 116 63
73 116 39 115 32 97 108 108 32 114 105 103 104 116 32 110 111 119 46
73 39 108 108 32 97 108 119 97 121 115 32 98 101 32 116 104 101 114 101 32 102 111 114 32 121 111 117 46
73 32 108 111 118 101 32 121 111 117 46
45 65 105 109 97 105 45"

This one is Unicode encoded. Once decoded, it becomes:

"To me.
It's been hard, hasn't it?
It's all right now.
I'll always be there for you.
Love you.
Aimai-"

Special thanks to Holbera.

"Have you ever heard of dust mushrooms? Dust mushroom is a mushroom that looks very similar to dust. It smells and tastes very similar to dust. No one can distinguish dust mushrooms from dust.
What's the difference, then? That's easy. Dust mushrooms are mushrooms!"

"There are tens of thousands of desserts in this world. It would be a waste of one's life to not have tried all of them.
Today, I am going on an expedition for desserts."

"Salmon, oh, salmon, who killed them? It is me, I did."

"To my beloved enemy. I promise you one thing. I will love you forever. I will also hate you forever. I love you. And that you die in eternity.
The blissful eternity is dead, and twilight will now come. When I cry, the hunter will come.
From the crow, who is purely yours, at your will.
October 7th, 1992."

"The pink cat is pink and cute. The pink cat needs proper attention and affection. If it doesn't get the attention it wants, it will meow out loud until you pay attention.
The pink cat has a secret. The pink cat is, actually a white rat. The white rat likes potato sprout. The sprout is in the poop that pink cat pooped 3 days ago.
The potato sprout likes a man with beautiful hands, curly hair and a mole below his eye who is 187cm tall and was born on 27th of September. The name of another pink cat, who is a friend of the pink cat, is Jang An-Chi. Jang An-Chi likes black hipster glasses."

"Enjoy the tea of happiness!
One sip, and the sweet taste of happiness will melt in your mouth and spread out to your whole body like the magic of a warm spring day! Come by if you're feeling blue and depressed.
Sit on the warm couch, listen to humming music, and have a cup of tea. All your sorrows and blues will be gone, and only happiness will remain!
Come to drink the tea of happiness!
Because you cannot feel happiness at the same temperature every time; we'll serve the tea according to your sorrow temperature. But be careful! If you're too greedy, your tongue and stomach will burn in the heat, and you may never feel happy again!"

"GREEN is a color that is simple, warm, friendly and grand. There once was a dwarf who loved GREEN. The dwarf was small, ordinary, depressed, and lacked social skills.
The dwarf wanted to become Green himself,
and so the dwarf walked into GREEN to become GREEN.
and...
the dwarf became and finally disappeared."

"* Chapter 3, Before Ordering*
Cheese meatballs are everyone's favorite, but if you order too much, you might end up with a cold platter. Be careful not to end up in a bad situation because of your lack of good luck."

"Ingredients: (Star) 1 Sun, 1 Horsehead Nebula, 8 Planets from the Solar System, 1/3 Arctic Aurora, 2 Biscuits

1. Plane a warm Sun on the biscuit.
   
2. Put a red Horsehead Nebula on it for the aromatic flavor.
   
3. Sprinkle 8 crunchy solar planets for a crispier texture.

Tip. The Astronomical Biscuit Sandwich goes great with a glass of Milky Way juice!"

"(...) "Women are flowers. All women are beautiful as they are." What an old fashioned cliché. This isn't exactly what I wanted to hear. Still, it is your attempt to compliment me......
But I don't have anything to say now. It's a common phrase, but I didn't want to respond in silence. That's why I said,
"If women are flowers, what are men?" I know, it is a strange question. Idioms or metaphors normally don't intend for contrasts.
I was feeling too self-conscious about my own question, so I couldn't tell that you were thinking. My heart dropped when I saw the coldness in your eyes. You gave it some thought and said,
"Well... Human, I guess.""

"Small, blue-green colored Newtto is ready to travel. He is excited to see what kind of adventures lie ahead of him. Let's go!
Oh, it's raining outside.
Never mind, adventures can wait. Newtto climbed back into the bed."

"Darkness existed long before light.
Light is nothing but a plaything created by Darkness. A small echo from the Darkness stretched its long legs and reached into the void, and so the universe was created.
We were born from the Darkness, and desire is the key that brings out our essence of being.
Light is only a savage, yet it ordered us to build societies and create gods that do not exist. Alas, how vast a concept!
How vain it all is.
But see, you are looking into the Darkness still."

"This is what I think. Making time by not sleeping is like pulling a rubber band. You keep pulling it backwards, but when you let go, you'll end up in a deep sleep to make up for all the sleep that you didn't sleep.
As for a rubber band in a bad shape like me, pulling is painful. You'll have to let go at one point if you pull the band too much. And then, it will fly away. Or it will snap. And you'll be a goner.
If I get a second chance, I want to be born as xylitol and prevent cavities. At least it will be a more fulfilling life."

"Tabby the cat has a long tail. That's why they call it "Tabby Tail".
Tabby's tail is so long, and keeps getting stepped on.
So the lesson is, be careful not to get your tail stepped on if you have a long tail."

"He stood alone, with a long black veil.
Little gemstones on the veil sprinkled light in many directions.
In the dark, I felt very calm."

"Just watch from a far distance. That is all that you can do.
Patience. But you know that won't be easy."

"What is a topping human? Topping humans are crunchy, sweet, and nutritious, so everyone loves to have them for snacks. They have self-consciousness and high intellectual abilities too, but they are only snacks for humans.
Poor topping human."