How to write it？
あかい
赤い、紅い、朱い、赫い
When writing ‘red’ in Japanese, we usually use kanji. You can see hiragana in books for children.
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赤い is most common.
紅い, 朱い, 赫い are often used in the titles of films or in novels.
They all describe ‘red’ and can be used for ordinal red.
But, depending on the situation, each of them means a specific colour.
紅, 朱 and 赫 means crimson, vermilion and scarlet, respectively.
They can be read in some ways in the word itself or with 色.
紅、紅色、紅色
朱、朱色、朱色
赫、赫色、赫色
I’m not sure if 赫色 is the correct pronunciation, but there is a yakitori shop in Japan called that.
I’ve never seen another example myself, but Japanese kanji allow people to read freely when it’s not an official situation. In that sense, I think that it can be possible and natural for 赫色 to have this pronunciation.
