四级

四 = 儿 + 囗 : Mnemonic symbol: a four-leaved clover. Socrates (s) is working out in the bathroom of the space station (Ø4). He's lifting four (四) wooden boxes (囗), and wonders why they are so heavy. He doesn't know that inside one of the four boxes, the monkey king (儿) is hiding and secretly laughing at him - until the monkey king comes out and surprises Socrates with a four-leaved clover (四).

级 = 及 + 纟 : Joan of Arc (ji) closely investigates her newly arrived troops just inside the space station's entrance (Ø2). She ranks (级) them according to their level (级): First there is a silk worm (纟) which can at least shapeshift. On the next level, there is Yuwen Huaji (及), who has no comparable super power.