The color of unripe bananas 青い (Aoi).
A "greenhorn" or other inexperienced person is also Aoi.
A youth / person in the springtime of their life is 青春.
A "greenhorn" or other inexperienced person is also Aoi.
A youth / person in the springtime of their life is 青春.
The etymology of that is different though. In Japanese it's because babies have a blue spot on their ass.