When a police officer holds an arm out horizontally, traffic facing that arm is being given the same meaning as a green light.

Explanation

For traffic facing the outstretched arm, the signal has the same meaning as a red light, so that traffic must stop. It is the traffic running parallel to the arm that gets the green meaning.

Guides that explain this

• Japanese Signs That Mean the Opposite of What You Assume: Crosswind, End of Restriction, Minimum Speed
• Japanese Road Signs on the Written Test: The 5 Types Explained

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