I've been calling it wrong all this time. I thought it's named White Lily but upon further research about this plant, it's specifically called Green-tinge Spiderlily.
Apparently, the shape of the flower looks like a spider except that these legs are lesser than what a spider should have. Anyway, I will not tinker any further about the name. Instead, I will simply admire this demure-looking flower. Actually, I think that the name is too badass for the way it looks.
It sounds scary for those who don't like 8-legged creatures but it's absolutely amazing as it stands out among the shaded area of our backyard.