There is only 2 variables you have to keep in mind. Favorability + Anger.
The time doesn't matter nor do the parts you click on to adjust the ratios.
Without spoiling much, the endings you get depend on the ratio between Favorability / Anger. (And one other thing...)

Kukula: (Will play a Voice Line after clicking each 5 times)
- Hand: 8 Favorability
- Head: 5 Favorability
- Horns: 5 Favorability | 3 Anger
- Wings: 3 Favorability | 5 Anger
- Lower Body: 8 anger
- Tail: 8 Anger
- Chest: 20 Anger

Other Clickable Objects:
- Hour-Glass: Makes a very loud reverberated drone
- Happiness Heart: Jumps Up and Down
- Anger Face: Makes a Sinister Laugh
- Settings Gear: Open Settings
- Tutorial Icon: Kukula will "Teach you how to act"
- Potion: *Clink* - Unlocks true ending (Gained after unlocking all endings and starting a new game)

Just get Kukula's Favorability and Anger between these margins
Ending 1 [Making a pact] - Favorability 80 - 100 | Anger 0 - 25
Ending 2 [Falling into chaos] - Favorability 0 - 25 | Anger 80 - 100
Ending 3 [Dodged a bullet] - 2 Cases [Favorability 1 - 50 | Anger 0 - 50] or [Favorability 0 - 50 | Anger 1 - 50]
Ending 4 [Being a toy boy] - Favorability 0 | Anger 0
Ending 5 [The slave of the devil] - Favorability 80 - 100 | Anger 80 - 100
Ending 6 [The devil roommate] - Favorability 80 - 100 | Anger 25 - 50
Ending 7 [The pet in the palm] - Favorability 25 - 50 | Anger 80 - 100
Ending 8 [The friend of the succubus] - Favorability 50 - 80 | Anger 50 - 80
Ending 9 [The seduction of big breasts] - Touch Kukula's Chest 5 times
True Ending [cherished ring] - Unlock all other endings + start new game and use the potion.

Thanks:
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3233524725
(Some info taken from)