Okay, I finished unlocking all the three main endings. For the third ending I need a help from Insane Side video because I was confused on where to look for the event trigger after getting out of the basement and walking aimlessly searching for it for more than 30 minutes. So I give credits to Insane Side too, thanks for the video!
But I didn't watch until the end to avoid spoilers on how the third ending will end, and I must say I was shocked on how it turns out. Leaving me speechless.