世界末日

世 = 廿 + L : Mnemonic symbol: the WTO or WHO.

Sherlock Holmes (sh) is cleaning a flower pot (廿) under the shower of the space station's bathroom (Ø4) with a loofah (L) because he didn't quite understand a poster next to the shower from the WHO (世) explaining dangers arising from different germs.

In this case, L is for loofah.

界 = 介 + 田 : Joan of Arc wants to leave this world and sets up a rocket launch field in the elevator's bathroom. The field looks like a normal crop field, except that there's a rocket in the middle and that the Joan of Arc marked the boundary with white and red tape.

末 = 一 + 木 : Mahatma Gandhi set up a giant flute on a Christmas tree, trying to raise awareness for the Roof of the World in the observatory's bathroom. He chose the flute and the tree as symbols for the sky and nature, but as Jehovah’s Witness enters, she thinks it's the sky that has fallen down on our heads, and the end of days is ultimately there.

日 = 囗 + 一 : Robinson Crusoe (r) is hiding from the sun (日) in an enclosure (囗) full of flutes (一) in the space station's bathroom (Ø4).