First off, you must complete Chapter 2. After that, all the chickens from the Chicken Coop in School will escape. You must gather all five chickens back to the coop. It can be all of them at once, or once at a time, or one bunch at a time. However, they will run from you unless you interact with them to follow you, and they'll eventually run away again unless you keep interacting with them time and time again.
Chicken Locations Edit
Chicken One Edit
On a small intersection south east from the School.
Chicken Two (Headless Chicken) Edit
On the road south of the School's main gate. There's a Floor Mouth nearby.
Chicken Three Edit
In the middle of the road right after the stairs where you are ambushed by Mr. Raw Heads, north of the School's main gate.
Chicken Four Edit
In the School's track and field.
It is recommended that you chase it "away" from the track and field full of Spirits.
Chicken Five Edit
In the School, in a small maze with some Headless Spirits.
This one is dangerous because the view is blocked by trees and there are Headless Spirits walking around and you will most likely already have 4 chickens impeding your movement.
Once you return all five chickens to the Chicken Coop, a Chicken Egg will appear inside of it for you to pick up.
Start with either the headless Chicken or Chicken 5 (in the small school maze)
Headless Chicken Route Edit
Interact with the Headless Chicken (Chicken 2), head north and follow the sidewalk northeast past the Siren Spirits, continue east until you find Chicken 1. Then head north, past the Mr. Raw Heads and keep going north until you find Chicken 3. Go back south, then go through the hole in the fence, heading southwest until you've reached the School Track, go around Chicken 4 in a wide circle, to chase it north; away from all the spirits on the track. Head southwest until you can go no further, the last chicken is southeast in a small maze with a few Headless Spirits. This is the most dangerous one. Headless Spirits are only visible in light but luckily cannot track the player very well, wait for an opening then grab the chicken. Head northwest to the Chicken Coup and run. A Blind Spirit is along the path, you can try sneaking past it, (or just run past it, as it's terrible at catching up)
Chicken 5 Route Edit
Start with Chicken 5 in the small school maze, then proceed to the Headless Chicken. This is a lower risk route, as Chicken 5 is the hardest to get. Then follow the guide above to get Chicken 1, Chicken 3, and Chicken 4. You may have to re-interact with Chicken 5.