All of these endings except Ending H require being on the last day. To get the ending cutscene, you'll rest in bed.

This page will obviously contain spoilers.

Ending A

On the final day: Have enough happiness to go to the in-store. Go to the river after. Do not pick up the bracelet before going to the river.

Ending B

On the final day: Have enough happiness to go to the in-store. Pick up the bracelet before going to the river.

Ending C

On the final day: Have your mood at 0 (Do not attend the in-store); Go to bed and sleep.

Ending D

On the final day: Do not go to the in-store. Get the bracelet and go to the river.

Ending E

On the final day: Go to the in-store. Pick up the bracelet.

Ending F

On the final day: Go to the in-store. Do not go to the river or pick up the bracelet.

Ending G

On the final day: Do not go to the in-store. Do not pick up the bracelet. Go to the river.

Ending H

On day 3, go to the shopping district at any point in time. Have some sort of eatable food in your inventory (i.e, something not like ketchup; something like omurice). Give food to Hachi 8 times and a cutscene will play out.

Note: To attend the in-store, you have to have a score of "3" or higher in your mood. While the number isn't shown in-game, pay attention to Arakawa's face in the paused menu.

Bracelet

You can only get this item on the final day. Go to the room you could not acess before with the switchblade in your pocket. Go up to the model and inspect it twice. You will get the bracelet.