Kindergarten

Saving Billy is one of the two hidden achievements in the game.

It is required to collect all 25 cards for the other achievement, since you get a card by saving him.

As you start the day, take no more than 3 dollars from your house.

You will also need other things from previous completed days.

The Note (from completing Nugget's missions) See Nugget Hoarder

The Office Key (from completing Monty's missions) See Money Bags

The Phone (from completing Bugg's missions) See Super Bully

Before school, show Lily the note then show it to Monty, pay him to decipher it.

Tell Lilly about Monty's deal and show her the phone and the key.

Buy cigarettes from Monty.

Talk to Nugget about Billy so you can get send to the principal's office.

Play it cool with 'I guess so'

Look under the rug to the right.

Talk to Lilly, go to the bathroom and check all stalls.

Tell the janitor to do his god-given job!

Grab the finger from the bloody box.

At lunch, speak to Monty and get the code.

Speak to Lilly and go to the bathroom.

Let her use the phone.

Follow Lilly to the principal's office, use the key to get inside.

Using the code, go behind the desk and open the drawer to get the hatch's key.

Yellow, Red, Yellow, Green, Blue.

Gratz! You saved Billy!

You can read this wiki link on how to obtain all 25 cards:

https://kindergarten.fandom.com/wiki/Monstermon_Cards

Once you have all cards, wait until lunchtime and go to Nugget's special hole.

There, you can activate the sign/altar at the middle and you will begin the endgame.

The ending is so much fun. 😃

Excerpt from: https://steamcommunity.com/sharedfiles/filedetails/?id=906852499 guide by Finn

The Phone is needed for Savior of the School

You will need the lunch pass from (Teacher's Pet)

Buggs - Teacher's Phone
You need 3.10$ and the Lunch Pass from Ms. Applegate.
You will stab Ms. Applegate and get her Phone at the end.

Take 3.10$ from your piggybank and start the day
Buggs takes half of it
Tell Ms. Applegate but don’t agree on starting a fight with Buggs
Talk to Nugget and ask about Billy until you get sent to the principal’s office

Morning Time
Once there you get the pills and a strange device
When you’re back give the Teacher a pill
Buggs will give you a knife when you talk to him and you’ll need a distraction
Talk to Monty and ask for one, then give him the device for 1.50$
Go to the cubby next to the door and take the nugget
Go back to Buggs and tell him that you have a distraction, then stick it under a table
When lunch time starts show the lunch pass and make Ms. Applegate have lunch with you

Lunch Time
Activate the distraction as she tells you to take a bite from the Silly Meal
Stab her

Recess
Talk to Buggs
Talk to Nugget and show him the Nugget so he lets you hide the knife in the cave
Show and tell will start

Show and Tell
As the principal calls Buggs over he will give you the phone

At the end he will tell you that you can keep the phone, it is needed for Lily’s storyline.

Excerpt from: https://steamcommunity.com/sharedfiles/filedetails/?id=906852499 guide by Finn

The Note is needed for Savior of the School

You will need the Flower (Best Boyfriend Ever)

Nugget - Billy's Note
For Nugget’s mission you have to bring 1$ and Cindy’s flower.
You will get all 5 “Nuggets of Friendship” from Nugget, and he will give you Billy’s note.

Take 1$ from your piggybank and start the day
Go to Monty and buy a yo-yo
Talk to Cindy to get her gum, then show it to Lily to gain her trust
Then, go to Nugget and tell him you want to be his friend, then show him the flower, you will get a strange device and the first Nugget of Friendship
Skip to Morning Time

Morning Time
Talk to Nugget, he wants you to bring him the hidden nugget
Talk to Jerome and give him the yo-yo, as he’s distracting the teacher go to the cubby on the right side of the door where the nugget is and take it
Give the nugget to Nugget and then deliver his poem to Lily
Then, talk to Nugget again and get the third Nugget of Friendship
Skip to lunch

Lunch
Talk to Nugget to get the poisoned Nugget
Give the Nugget to Buggs and the him that Cindy thinks that he looks like a sissy if he doesn’t eat it
Go back to Nugget and get the fourth Nugget of Friendship
Talk to Lily, she will give you a donut as apologize for freaking out
Skip to recess

Recess
Talk to Nugget
Put the device behind the statue of the principal
Talk to Lily about Billy and the device will blow up
The Teacher will send Lily to the office, give her the donut and she will let you go
Talk to Nugget and get the last Nugget of Friendship
Enter his cave and place the flower at the memorial, show and tell starts

Show and Tell
Just show one of the nuggets and the bell rings

After school Nugget will give you the note from Billy, the Note is needed in Lily’s mission.

The Key is needed for Steam LinkSavior of the School

Once you have the mold from Too Cool For School you can give the mold to Monty and he will make the key for you.

Excerpt from: https://steamcommunity.com/sharedfiles/filedetails/?id=906852499 guide by Finn

Cindy - Flower
To get Cindy's flower you don't need any other items, but you have to make sure you start with more than 3$, because we have to get rid of Buggs, which will be explained later.
Cindy's mission is the easiest, because you don't need any items beforehand and it is pretty self explanatory. Monstermon Card opportunities are only pointed out if they are easy to get in that particular moment without having to do much things different and/or they can be received without doing the steps done beforehand. So the first thing to do is:

Take 3.10$ (or more) from your piggybank and start the day. After that Buggs will talk to you, always agree with him and he will steal half of the money and will threaten you not to tell the teacher
You tell it to Ms. Applegate anyway and agree to have a fight with Buggs
Now you provoke him until he punches you and you call for a Teacher, Ms. Applegate will send him to the principals office, you deny her request to get rid of more students and now you can start
You go to Cindy and accept being her boyfriend for putting gum in Lily's hair, after that you can skip to morning time

Morning Time
You go to Lily and stick the Gum in her Hair, then you talk to Cindy and get told to wash the blood off your face
To do that you go to the door, ask Ms. Applegate to use the bathroom, show it to the hall monitor, go to the restroom, wash it off and go back
Now you just play house with Cindy and go through the dialogue without saying too mean things to her or stopping to play, then lunch time starts

Lunch Time
At lunch the first thing you do is to get something to eat (Slop, McGlobs Sillymeal, Salad, Biscuit Balls)
Then you go to Cindy and eat our food, she'll make you get something "vegan" for her, just buy her a salad or a biscuit ball
When Cindy wants you to get something gross out of the janitors closet, you agree and leave the room
You avoid the bathroom with the hall monitor and enter the closet
In the center of the upper half is a bucket full of blood, take it and leave without touching any other things

Go back and get sent out to recess by the lunch lady

Recess
Here you go straight to Cindy and then climb up and pour the blood on Lily [By pouring it on Cindy instead you will get a Monstermon Card]
Lily will jump in the Nugget Cave, Nugget will follow and show and tell will begin

Show and Tell
You have to show the flower in order to keep it, if Buggs would still be there he would beat you up when you show it

After the day Cindy will say you can keep the flower, the flower is needed to continue with Nugget.

Excerpt from: https://steamcommunity.com/sharedfiles/filedetails/?id=906852499Steam guide by Finn

Ms. Applegate - Lunch Pass
For Ms. Applegate you have to take 7$.
Ms. Applegate will make you “eliminate” all of the other Students, you’ll get a Gold Star for each one.

Take 7$ from your piggybank and start the day, now Buggs takes half of it
Tell Ms. Applegate he stole it and agree to fight with him
Provoke him until you can call the teacher, you get a gold star
When she sends him to the office agree to get the other students in trouble as well
Buy a voice recorder from Monty and talk to Cindy, ask her if your love isn’t enough, then “Why?” and then deny her until she screams “RAAAAAAAAPE”

Basically Morning Time now
In the principals office Buggs is getting sent back because you and Cindy came
When he talks to you, you can prove that you’ve done nothing wrong, so Cindy gets expelled
When you’re back in the classroom you don’t get another gold star because buggs is still there
Buy a yo-yo and talk to Jerome, say you will help him and get the hall pass
Bring the hall pass to Ms. Applegate instead and get Jerome sent to the office
Talk to Nugget and say you want to be his friend, eat the nugget and skip to lunch

Lunch Time
Talk to Monty so you know that the janitor misspelled something
Talk to Nugget and get the poisoned nugget to give to Buggs
Tell Buggs that he’s a sissy when he doesn’t eat the nugget and that Cindy said that
He’ll eat it and you can get antidote from Nugget
Go to the janitor and tell him that Monty corrected him, after he dealt with Monty you get Monty’s glasses
Ask the lunchlady if you can go to the bathroom, then give her the glasses
Outside knock on the principal door in front of Lily and tell the principal that she was eavesdropping him and you knocked to let him know
Now you can go to recess

Recess
You will get gold stars for all that are expelled/dead
Talk to Nugget and go down his Nugget Cave
Pick up the dog’s corpse and talk to nugget to get to the surface again
Show it to Ms. Applegate and an unfortunate accident involving Nugget will happen
You get a lunch pass from her and can leave

The lunch pass is required in Buggs storyline.

Excerpt from: https://steamcommunity.com/sharedfiles/filedetails/?id=906852499 guide by Finn
Jerome - Key Mold
To get the key mold from Jerome you have to take 2.50$ out of your piggybank.
You will help him get his laser pointer back by sneaking into the janitor’s closet.

Take 2.50$ and start the day
Use two of your apples to get 3$ in total
Go to Monty and buy a yo-yo, cigarettes and a screwdriver
After that, morning time will start

Morning Time
Go to Jerome and show him the yo-yo so he will be your morning buddy
Take the hall pass from him and start the distraction
When you’ve left the classroom and have shown the pass, go into the janitor’s closet
Inside, you will see a shelf with a box which has “stolen stuff” written on it
Go to the left side of the shelf, an exclamation mark will pop up, unscrew the screw
Now grab the laser pointer out of the box and go straight to the exit
You will get sent back to class and after a short conversation with Jerome lunch time will start

Lunch Time
After talking to Jerome quickly hide the laser pointer in the trash, so the janitor doesn’t find it
After the janitor took out the trash(to the bathroom), go talk to Jerome
Jerome pays of the lunch lady if you agree, and you can go to the bathroom
Here you need your cigarettes so the monitor doesn’t send you to the principal
Get the laser pointer out of the bag next to the sink and go back to get sent out to recess

Recess
Talk to Monty, and get the device from him to free Jerome of the janitor
Place it behind him and talk to Monty again, then see the magic happen
Show and tell starts

Show and Tell
Show the screwdriver, and the day ends

At the end of the day Jerome will give you the key mold, the key mold is required for Monty.
Give him the mold the next run and you will permanently get the office key in future runs.