I've got the first statue, used it on the archive room.

Now I know that the second statue is in Samoa's bedroom, but I can't find a way to get it.

There's a hint: "Touch some water with my bare skin (why is that?)... best way: have bowl of water next to bed"

Well, there's a different hint which is the right hint to help you get the second statue. But I won't spoil it here. Hope the mods or admins could just delete this post for me. Thank you!!

I've got the second statue during the night from the shop. It was actually the first one I've got. I woke up in night on my first try with an alarm clock after the day when I was fixing the well (did that fill the condition to touch the water?).

I suspect that "touch the water to skin" thing is likely referring to how you can make someone want to go to the toilet in the middle of the night (and hence wake up) by putting their hand in a bowl of warm water.

I don't think there's any direct relation to any puzzle solution - except for the fact it's yet another thing mentioning that waking up in the middle of the night is important.