Steep descent
下り急勾配あり(くだりきゅうこうばいあり)
Meaning
A warning sign indicating a steep downhill slope ahead. Speed builds up easily and brakes can overheat, so use engine braking as well.
Common mistake on the test
A section where you should avoid overusing the foot brake and use engine braking. Tell it apart from the ascent sign (212-3) by the direction of the design.