Oh, sorry, I don't know what "whaleshares" is. Here in the Chinese idiom 赤橙黄绿青蓝紫, 青 is blue, 蓝 is indigo. I guess maybe it is because in ancient Chinese, 蓝means a kind of grass used as dyestuff. Just like this famous Chinese idiom: 青出于蓝而胜于蓝"Blue is extracted from the indigo plant, but it is bluer than it." You're right, in ancient Chinese, 青 is the same as Japanese, 青 means blue.
But in modern Chinese, 蓝 is blue, 青 is azury. 赤 still means red.
I am very ignorant about Japanese. It is said that people can find a lot of Chinese characters in ancient Japanese books. However, I don't think their pronunciations are the same.
蓝's pronunciation in Chinese is "lan", 赤 is "chi".